Backport "bpf, arm64: Reject out-of-range B.cond targets" in 6.6 by shunghsiyu · Pull Request #7 · kernel-patches/linux-stable

shunghsiyu · 2026-07-03T05:21:08Z

commit 48d83d9 upstream.

aarch64_insn_gen_cond_branch_imm() calls label_imm_common() to compute a 19-bit signed byte offset for a conditional branch, but unlike its siblings aarch64_insn_gen_branch_imm() and aarch64_insn_gen_comp_branch_imm(), it does not check whether label_imm_common() returned its out-of-range sentinel (range) before feeding the value to aarch64_insn_encode_immediate().

aarch64_insn_encode_immediate() unconditionally masks the value with the 19-bit field mask, so an offset that was rejected by label_imm_common() gets silently truncated. With the sentinel value SZ_1M, the resulting field ends up with bit 18 (the sign bit of the 19-bit signed displacement) set, and the CPU decodes it as a ~1 MiB backward branch, producing an incorrectly targeted B.cond instruction. For code-gen locations like the emit_bpf_tail_call() this function is the only barrier between an overflowing displacement and a silently miscompiled branch.

Fix it by returning AARCH64_BREAK_FAULT when the offset is out of range, so callers see a loud failure instead of a silently misencoded branch. validate_code() scans the generated image for any AARCH64_BREAK_FAULT and then lets the JIT fail.

Fixes: 345e0d3 ("arm64: introduce aarch64_insn_gen_cond_branch_imm()")
Fixes: c94ae4f ("arm64: insn: remove BUG_ON from codegen")

Reviewed-by: Puranjay Mohan puranjay@kernel.org
Link: https://lore.kernel.org/r/20260415121403.639619-1-daniel@iogearbox.net

commit 48d83d9 upstream. aarch64_insn_gen_cond_branch_imm() calls label_imm_common() to compute a 19-bit signed byte offset for a conditional branch, but unlike its siblings aarch64_insn_gen_branch_imm() and aarch64_insn_gen_comp_branch_imm(), it does not check whether label_imm_common() returned its out-of-range sentinel (range) before feeding the value to aarch64_insn_encode_immediate(). aarch64_insn_encode_immediate() unconditionally masks the value with the 19-bit field mask, so an offset that was rejected by label_imm_common() gets silently truncated. With the sentinel value SZ_1M, the resulting field ends up with bit 18 (the sign bit of the 19-bit signed displacement) set, and the CPU decodes it as a ~1 MiB *backward* branch, producing an incorrectly targeted B.cond instruction. For code-gen locations like the emit_bpf_tail_call() this function is the only barrier between an overflowing displacement and a silently miscompiled branch. Fix it by returning AARCH64_BREAK_FAULT when the offset is out of range, so callers see a loud failure instead of a silently misencoded branch. validate_code() scans the generated image for any AARCH64_BREAK_FAULT and then lets the JIT fail. Fixes: 345e0d3 ("arm64: introduce aarch64_insn_gen_cond_branch_imm()") Fixes: c94ae4f ("arm64: insn: remove BUG_ON from codegen") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Puranjay Mohan <puranjay@kernel.org> Link: https://lore.kernel.org/r/20260415121403.639619-1-daniel@iogearbox.net Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>

commit 4721f81 upstream. When checking if a VP ID is included in a sparse bank set, explicitly check that the ID can actually be contained in a sparse bank (the TLFS allows for a maximum of 64 banks of 64 vCPUs each). When handling a paravirtual TLB flush for L2, the VP ID is copied verbatim from the enlightened VMCS, without any bounds check, i.e. isn't guaranteed to be under the limit of 4096. Failure to check the bounds of the VP ID leads to an out-of-bounds read when testing the sparse bank, and super strictly speaking could lead to KVM performing an unnecessary TLB flush for an L2 vCPU. ================================================================== BUG: KASAN: use-after-free in hv_is_vp_in_sparse_set+0x85/0x100 [kvm] Read of size 8 at addr ffff88811ba5f598 by task hyperv_evmcs/2802 CPU: 12 UID: 1000 PID: 2802 Comm: hyperv_evmcs Not tainted 7.1.0-rc2 #7 PREEMPT Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 Call Trace: <TASK> dump_stack_lvl+0x51/0x60 print_report+0xcb/0x5d0 kasan_report+0xb4/0xe0 kasan_check_range+0x35/0x1b0 hv_is_vp_in_sparse_set+0x85/0x100 [kvm] kvm_hv_flush_tlb+0xe9e/0x16c0 [kvm] kvm_hv_hypercall+0xe6b/0x1e60 [kvm] vmx_handle_exit+0x485/0x1b60 [kvm_intel] kvm_arch_vcpu_ioctl_run+0x22e3/0x5070 [kvm] kvm_vcpu_ioctl+0x5d0/0x10c0 [kvm] __x64_sys_ioctl+0x129/0x1a0 do_syscall_64+0xb9/0xcf0 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x7f0e62d1a9bf </TASK> The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffffffffffffffff pfn:0x11ba5f flags: 0x4000000000000000(zone=1) raw: 4000000000000000 0000000000000000 00000000ffffffff 0000000000000000 raw: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88811ba5f480: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff88811ba5f500: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff88811ba5f580: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff88811ba5f600: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff88811ba5f680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ================================================================== Disabling lock debugging due to kernel taint Opportunistically add a compile time assertion to ensure the maximum number of sparse banks exactly matches the number of possible bits in the passed in mask. Cc: stable@vger.kernel.org Fixes: c58a318 ("KVM: x86: hyper-v: L2 TLB flush") Signed-off-by: Hyunwoo Kim <imv4bel@gmail.com> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com> Link: https://patch.msgid.link/aiQyZIJtO-2Aj_xN@v4bel [sean: add KASAN splat, drop comment, add assert, massage changelog] Signed-off-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

sco_sock_timeout() runs asynchronously and lock_sock(sk). If the socket is closing while the timer is running, it holds the same lock (lock_sock(sk)) twice, leading to a deadlock. CPU 0 CPU 1 ==================== ====================== sco_sock_close() sco_sock_timeout() lock_sock(sk) // <-- LOCK __sco_sock_close() sco_chan_del() sco_conn_put() sco_conn_free() disable_delayed_work_sync() lock(sk) // <-- SAME LOCK Fix this by moving disable_delayed_work_sync() outside of lock_sock(sk), ensuring that no lock_sock(sk) is held before sco_sock_timeout(). Lockdep splat: WARNING: possible circular locking dependency detected 6.13.0-rc4 #7 Not tainted syz-executor292/9514 is trying to acquire lock: ffff8881115d5070 ((work_completion)(&(&conn->timeout_work)->work)){+.+.}-{0:0}, at: rcu_lock_acquire sect/v6.13-rc4/./include/linux/rcupdate.h:337 [inline] ffff8881115d5070 ((work_completion)(&(&conn->timeout_work)->work)){+.+.}-{0:0}, at: rcu_read_lock sect/v6.13-rc4/./include/linux/rcupdate.h:849 [inline] ffff8881115d5070 ((work_completion)(&(&conn->timeout_work)->work)){+.+.}-{0:0}, at: start_flush_work sect/v6.13-rc4/kernel/workqueue.c:4137 [inline] ffff8881115d5070 ((work_completion)(&(&conn->timeout_work)->work)){+.+.}-{0:0}, at: __flush_work+0xd1/0xc40 sect/v6.13-rc4/kernel/workqueue.c:4195 but task is already holding lock: ffff88807db3a258 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: lock_sock sect/v6.13-rc4/./include/net/sock.h:1623 [inline] ffff88807db3a258 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: sco_sock_close+0x25/0x100 sect/v6.13-rc4/net/bluetooth/sco.c:524 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}: lock_acquire+0x1c4/0x520 sect/v6.13-rc4/kernel/locking/lockdep.c:5849 lock_sock_nested+0x48/0x130 sect/v6.13-rc4/net/core/sock.c:3622 lock_sock sect/v6.13-rc4/./include/net/sock.h:1623 [inline] sco_sock_timeout+0xbe/0x270 sect/v6.13-rc4/net/bluetooth/sco.c:158 process_one_work sect/v6.13-rc4/kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa99/0x18f0 sect/v6.13-rc4/kernel/workqueue.c:3310 worker_thread+0x8a9/0xd80 sect/v6.13-rc4/kernel/workqueue.c:3391 kthread+0x2c6/0x360 sect/v6.13-rc4/kernel/kthread.c:389 ret_from_fork+0x4e/0x80 sect/v6.13-rc4/arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 sect/v6.13-rc4/arch/x86/entry/entry_64.S:244 -> #0 ((work_completion)(&(&conn->timeout_work)->work)){+.+.}-{0:0}: check_prev_add sect/v6.13-rc4/kernel/locking/lockdep.c:3161 [inline] check_prevs_add sect/v6.13-rc4/kernel/locking/lockdep.c:3280 [inline] validate_chain+0x1888/0x5760 sect/v6.13-rc4/kernel/locking/lockdep.c:3904 __lock_acquire+0x13b4/0x2120 sect/v6.13-rc4/kernel/locking/lockdep.c:5226 lock_acquire+0x1c4/0x520 sect/v6.13-rc4/kernel/locking/lockdep.c:5849 touch_work_lockdep_map sect/v6.13-rc4/kernel/workqueue.c:3909 [inline] start_flush_work sect/v6.13-rc4/kernel/workqueue.c:4163 [inline] __flush_work+0x70f/0xc40 sect/v6.13-rc4/kernel/workqueue.c:4195 __cancel_work_sync sect/v6.13-rc4/kernel/workqueue.c:4351 [inline] disable_delayed_work_sync+0xbb/0xf0 sect/v6.13-rc4/kernel/workqueue.c:4514 sco_conn_free sect/v6.13-rc4/net/bluetooth/sco.c:95 [inline] kref_put sect/v6.13-rc4/./include/linux/kref.h:65 [inline] sco_conn_put+0x18f/0x270 sect/v6.13-rc4/net/bluetooth/sco.c:107 sco_chan_del+0xe2/0x210 sect/v6.13-rc4/net/bluetooth/sco.c:236 sco_sock_close+0x8f/0x100 sect/v6.13-rc4/net/bluetooth/sco.c:526 sco_sock_release+0x62/0x2d0 sect/v6.13-rc4/net/bluetooth/sco.c:1300 __sock_release+0xe1/0x2d0 sect/v6.13-rc4/net/socket.c:640 sock_close+0x1c/0x30 sect/v6.13-rc4/net/socket.c:1408 __fput+0x2bd/0xa80 sect/v6.13-rc4/fs/file_table.c:450 __fput_sync+0x15e/0x1c0 sect/v6.13-rc4/fs/file_table.c:535 __do_sys_close sect/v6.13-rc4/fs/open.c:1554 [inline] __se_sys_close sect/v6.13-rc4/fs/open.c:1539 [inline] __x64_sys_close+0x93/0x120 sect/v6.13-rc4/fs/open.c:1539 do_syscall_x64 sect/v6.13-rc4/arch/x86/entry/common.c:52 [inline] do_syscall_64+0xee/0x210 sect/v6.13-rc4/arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f Fixes: e672077 ("Bluetooth: SCO: Use kref to track lifetime of sco_conn") Acked-by: Dave Tian <daveti@purdue.edu> Signed-off-by: Sungwoo Kim <iam@sung-woo.kim> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

[ Upstream commit b23705e ] strset_add_str_mem() might reallocate the strset data buffer in order to accommodate the provided string 's'. However, if 's' points to a string already present in the buffer, it becomes dangling after the realloc. This leads to a use-after-free when attempting to memcpy() the string into the new buffer. One scenario that triggers this problematic path is when resolve_btfids attempts to patch kfunc prototypes using existing BTF parameter names: | resolve_btfids: function bpf_list_push_back_impl already exists in BTF | Segmentation fault (core dumped) Compiling resolve_btfids with fsanitize=address generates a detailed report of the UAF: | ================================================================= | ERROR: AddressSanitizer: heap-use-after-free on address 0x7f4c4a500bd4 | ==1507892==ERROR: AddressSanitizer: heap-use-after-free on address 0x7f4c4a500bd4 at pc 0x55d25155a2a8 bp 0x7ffcef879060 sp 0x7ffcef878818 | READ of size 5 at 0x7f4c4a500bd4 thread T0 | #0 0x55d25155a2a7 in memcpy (tools/bpf/resolve_btfids/resolve_btfids+0xcf2a7) | #1 0x55d2515d708e in strset__add_str tools/lib/bpf/strset.c:162:2 | #2 0x55d2515c730b in btf__add_str tools/lib/bpf/btf.c:2109:8 | #3 0x55d2515c9020 in btf__add_func_param tools/lib/bpf/btf.c:3108:14 | #4 0x55d25159f0b5 in process_kfunc_with_implicit_args tools/bpf/resolve_btfids/main.c:1196:9 | #5 0x55d25159e004 in btf2btf tools/bpf/resolve_btfids/main.c:1229:9 | #6 0x55d25159cee7 in main tools/bpf/resolve_btfids/main.c:1535:6 | #7 0x7f4c78e29f76 in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16 | #8 0x7f4c78e2a026 in __libc_start_main csu/../csu/libc-start.c:360:3 | #9 0x55d2514bb860 in _start (tools/bpf/resolve_btfids/resolve_btfids+0x30860) | | 0x7f4c4a500bd4 is located 13268 bytes inside of 2829000-byte region [0x7f4c4a4fd800,0x7f4c4a7b02c8) | freed by thread T0 here: | #0 0x55d25155b700 in realloc (tools/bpf/resolve_btfids/resolve_btfids+0xd0700) | #1 0x55d2515c426c in libbpf_reallocarray tools/lib/bpf/./libbpf_internal.h:220:9 | #2 0x55d2515c426c in libbpf_add_mem tools/lib/bpf/btf.c:224:13 | | previously allocated by thread T0 here: | #0 0x55d25155b2e3 in malloc (tools/bpf/resolve_btfids/resolve_btfids+0xd02e3) | #1 0x55d2515d6e7d in strset__new tools/lib/bpf/strset.c:58:20 While resolve_btfids could be refactored to avoid this call path, let's instead fix this issue at the source in strset__add_str() and avoid similar scenarios. Let's check if set->strs_data was reallocated and whether 's' points to an internal string within the old strset buffer. In such case, 's' is reconstructed to point to the new buffer. While already here, also fix strset__find_str() which suffers from the same problem by factoring out the common operations into a new helper function strset_str_append(). Fixes: 90d76d3 ("libbpf: Extract internal set-of-strings datastructure APIs") Suggested-by: Andrii Nakryiko <andrii@kernel.org> Suggested-by: Mykyta Yatsenko <yatsenko@meta.com> Signed-off-by: Carlos Llamas <cmllamas@google.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20260523162722.2718940-1-cmllamas@google.com Signed-off-by: Sasha Levin <sashal@kernel.org>

[ Upstream commit 0f8a5dc ] sco_sock_timeout() runs asynchronously and lock_sock(sk). If the socket is closing while the timer is running, it holds the same lock (lock_sock(sk)) twice, leading to a deadlock. CPU 0 CPU 1 ==================== ====================== sco_sock_close() sco_sock_timeout() lock_sock(sk) // <-- LOCK __sco_sock_close() sco_chan_del() sco_conn_put() sco_conn_free() disable_delayed_work_sync() lock(sk) // <-- SAME LOCK Fix this by moving disable_delayed_work_sync() outside of lock_sock(sk), ensuring that no lock_sock(sk) is held before sco_sock_timeout(). Lockdep splat: WARNING: possible circular locking dependency detected 6.13.0-rc4 #7 Not tainted syz-executor292/9514 is trying to acquire lock: ffff8881115d5070 ((work_completion)(&(&conn->timeout_work)->work)){+.+.}-{0:0}, at: rcu_lock_acquire sect/v6.13-rc4/./include/linux/rcupdate.h:337 [inline] ffff8881115d5070 ((work_completion)(&(&conn->timeout_work)->work)){+.+.}-{0:0}, at: rcu_read_lock sect/v6.13-rc4/./include/linux/rcupdate.h:849 [inline] ffff8881115d5070 ((work_completion)(&(&conn->timeout_work)->work)){+.+.}-{0:0}, at: start_flush_work sect/v6.13-rc4/kernel/workqueue.c:4137 [inline] ffff8881115d5070 ((work_completion)(&(&conn->timeout_work)->work)){+.+.}-{0:0}, at: __flush_work+0xd1/0xc40 sect/v6.13-rc4/kernel/workqueue.c:4195 but task is already holding lock: ffff88807db3a258 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: lock_sock sect/v6.13-rc4/./include/net/sock.h:1623 [inline] ffff88807db3a258 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: sco_sock_close+0x25/0x100 sect/v6.13-rc4/net/bluetooth/sco.c:524 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}: lock_acquire+0x1c4/0x520 sect/v6.13-rc4/kernel/locking/lockdep.c:5849 lock_sock_nested+0x48/0x130 sect/v6.13-rc4/net/core/sock.c:3622 lock_sock sect/v6.13-rc4/./include/net/sock.h:1623 [inline] sco_sock_timeout+0xbe/0x270 sect/v6.13-rc4/net/bluetooth/sco.c:158 process_one_work sect/v6.13-rc4/kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa99/0x18f0 sect/v6.13-rc4/kernel/workqueue.c:3310 worker_thread+0x8a9/0xd80 sect/v6.13-rc4/kernel/workqueue.c:3391 kthread+0x2c6/0x360 sect/v6.13-rc4/kernel/kthread.c:389 ret_from_fork+0x4e/0x80 sect/v6.13-rc4/arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 sect/v6.13-rc4/arch/x86/entry/entry_64.S:244 -> #0 ((work_completion)(&(&conn->timeout_work)->work)){+.+.}-{0:0}: check_prev_add sect/v6.13-rc4/kernel/locking/lockdep.c:3161 [inline] check_prevs_add sect/v6.13-rc4/kernel/locking/lockdep.c:3280 [inline] validate_chain+0x1888/0x5760 sect/v6.13-rc4/kernel/locking/lockdep.c:3904 __lock_acquire+0x13b4/0x2120 sect/v6.13-rc4/kernel/locking/lockdep.c:5226 lock_acquire+0x1c4/0x520 sect/v6.13-rc4/kernel/locking/lockdep.c:5849 touch_work_lockdep_map sect/v6.13-rc4/kernel/workqueue.c:3909 [inline] start_flush_work sect/v6.13-rc4/kernel/workqueue.c:4163 [inline] __flush_work+0x70f/0xc40 sect/v6.13-rc4/kernel/workqueue.c:4195 __cancel_work_sync sect/v6.13-rc4/kernel/workqueue.c:4351 [inline] disable_delayed_work_sync+0xbb/0xf0 sect/v6.13-rc4/kernel/workqueue.c:4514 sco_conn_free sect/v6.13-rc4/net/bluetooth/sco.c:95 [inline] kref_put sect/v6.13-rc4/./include/linux/kref.h:65 [inline] sco_conn_put+0x18f/0x270 sect/v6.13-rc4/net/bluetooth/sco.c:107 sco_chan_del+0xe2/0x210 sect/v6.13-rc4/net/bluetooth/sco.c:236 sco_sock_close+0x8f/0x100 sect/v6.13-rc4/net/bluetooth/sco.c:526 sco_sock_release+0x62/0x2d0 sect/v6.13-rc4/net/bluetooth/sco.c:1300 __sock_release+0xe1/0x2d0 sect/v6.13-rc4/net/socket.c:640 sock_close+0x1c/0x30 sect/v6.13-rc4/net/socket.c:1408 __fput+0x2bd/0xa80 sect/v6.13-rc4/fs/file_table.c:450 __fput_sync+0x15e/0x1c0 sect/v6.13-rc4/fs/file_table.c:535 __do_sys_close sect/v6.13-rc4/fs/open.c:1554 [inline] __se_sys_close sect/v6.13-rc4/fs/open.c:1539 [inline] __x64_sys_close+0x93/0x120 sect/v6.13-rc4/fs/open.c:1539 do_syscall_x64 sect/v6.13-rc4/arch/x86/entry/common.c:52 [inline] do_syscall_64+0xee/0x210 sect/v6.13-rc4/arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f Fixes: e672077 ("Bluetooth: SCO: Use kref to track lifetime of sco_conn") Acked-by: Dave Tian <daveti@purdue.edu> Signed-off-by: Sungwoo Kim <iam@sung-woo.kim> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com> Signed-off-by: Sasha Levin <sashal@kernel.org>