linux-kernel - [PATCH] bpf: Fix bpf_prog nested call in trace_mmap_lock_acquire

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20250512145901.691685-1-chen.dylane@linux.dev>
Date: Mon, 12 May 2025 22:59:01 +0800
From: Tao Chen <chen.dylane@...ux.dev>
To: song@...nel.org,
	jolsa@...nel.org,
	ast@...nel.org,
	daniel@...earbox.net,
	andrii@...nel.org,
	martin.lau@...ux.dev,
	eddyz87@...il.com,
	yonghong.song@...ux.dev,
	john.fastabend@...il.com,
	kpsingh@...nel.org,
	sdf@...ichev.me,
	haoluo@...gle.com,
	Liam.Howlett@...cle.com
Cc: bpf@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Tao Chen <chen.dylane@...ux.dev>,
	syzbot+45b0c89a0fc7ae8dbadc@...kaller.appspotmail.com
Subject: [PATCH] bpf: Fix bpf_prog nested call in trace_mmap_lock_acquire_returned

syzkaller reported an issue:

 bpf_prog_ec3b2eefa702d8d3+0x43/0x47
 bpf_dispatcher_nop_func include/linux/bpf.h:1316 [inline]
 __bpf_prog_run include/linux/filter.h:718 [inline]
 bpf_prog_run include/linux/filter.h:725 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2363 [inline]
 bpf_trace_run3+0x23f/0x5a0 kernel/trace/bpf_trace.c:2405
 __bpf_trace_mmap_lock_acquire_returned+0xfc/0x140 include/trace/events/mmap_lock.h:47
 __traceiter_mmap_lock_acquire_returned+0x79/0xc0 include/trace/events/mmap_lock.h:47
 __do_trace_mmap_lock_acquire_returned include/trace/events/mmap_lock.h:47 [inline]
 trace_mmap_lock_acquire_returned include/trace/events/mmap_lock.h:47 [inline]
 __mmap_lock_do_trace_acquire_returned+0x138/0x1f0 mm/mmap_lock.c:35
 __mmap_lock_trace_acquire_returned include/linux/mmap_lock.h:36 [inline]
 mmap_read_trylock include/linux/mmap_lock.h:204 [inline]
 stack_map_get_build_id_offset+0x535/0x6f0 kernel/bpf/stackmap.c:157
 __bpf_get_stack+0x307/0xa10 kernel/bpf/stackmap.c:483
 ____bpf_get_stack kernel/bpf/stackmap.c:499 [inline]
 bpf_get_stack+0x32/0x40 kernel/bpf/stackmap.c:496
 ____bpf_get_stack_raw_tp kernel/trace/bpf_trace.c:1941 [inline]
 bpf_get_stack_raw_tp+0x124/0x160 kernel/trace/bpf_trace.c:1931
 bpf_prog_ec3b2eefa702d8d3+0x43/0x47
 bpf_dispatcher_nop_func include/linux/bpf.h:1316 [inline]
 __bpf_prog_run include/linux/filter.h:718 [inline]
 bpf_prog_run include/linux/filter.h:725 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2363 [inline]
 bpf_trace_run3+0x23f/0x5a0 kernel/trace/bpf_trace.c:2405
 __bpf_trace_mmap_lock_acquire_returned+0xfc/0x140 include/trace/events/mmap_lock.h:47
 __traceiter_mmap_lock_acquire_returned+0x79/0xc0 include/trace/events/mmap_lock.h:47
 __do_trace_mmap_lock_acquire_returned include/trace/events/mmap_lock.h:47 [inline]
 trace_mmap_lock_acquire_returned include/trace/events/mmap_lock.h:47 [inline]
 __mmap_lock_do_trace_acquire_returned+0x138/0x1f0 mm/mmap_lock.c:35
 __mmap_lock_trace_acquire_returned include/linux/mmap_lock.h:36 [inline]
 mmap_read_lock include/linux/mmap_lock.h:185 [inline]
 exit_mm kernel/exit.c:565 [inline]
 do_exit+0xf72/0x2c30 kernel/exit.c:940
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1102
 __do_sys_exit_group kernel/exit.c:1113 [inline]
 __se_sys_exit_group kernel/exit.c:1111 [inline]
 __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1111
 x64_sys_call+0x1530/0x1730 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

mmap_read_trylock is used in stack_map_get_build_id_offset, if user
wants to trace trace_mmap_lock_acquire_returned tracepoint and get user
stack in the bpf_prog, it will call trace_mmap_lock_acquire_returned
again in the bpf_get_stack, which will lead to a nested call relationship.

Reported-by: syzbot+45b0c89a0fc7ae8dbadc@...kaller.appspotmail.com
Closes: https://lore.kernel.org/bpf/8bc2554d-1052-4922-8832-e0078a033e1d@gmail.com
Fixes: 2f1aaf3ea666 ("bpf, mm: Fix lockdep warning triggered by stack_map_get_build_id_offset()")
Signed-off-by: Tao Chen <chen.dylane@...ux.dev>
---
 kernel/bpf/stackmap.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c
index 3615c06b7dfa..eec51f069028 100644
--- a/kernel/bpf/stackmap.c
+++ b/kernel/bpf/stackmap.c
@@ -130,6 +130,10 @@ static int fetch_build_id(struct vm_area_struct *vma, unsigned char *build_id, b
 			 : build_id_parse_nofault(vma, build_id, NULL);
 }
 
+static inline bool mmap_read_trylock_no_trace(struct mm_struct *mm)
+{
+	return down_read_trylock(&mm->mmap_lock) != 0;
+}
 /*
  * Expects all id_offs[i].ip values to be set to correct initial IPs.
  * They will be subsequently:
@@ -154,7 +158,7 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs,
 	 * build_id.
 	 */
 	if (!user || !current || !current->mm || irq_work_busy ||
-	    !mmap_read_trylock(current->mm)) {
+	    !mmap_read_trylock_no_trace(current->mm)) {
 		/* cannot access current->mm, fall back to ips */
 		for (i = 0; i < trace_nr; i++) {
 			id_offs[i].status = BPF_STACK_BUILD_ID_IP;
-- 
2.43.0