* [PATCH] tracing/kprobes: fix NULL pointer dereference in trace_kprobe_create()
@ 2019-01-10 17:39 Andrea Righi
2019-01-11 0:51 ` Masami Hiramatsu
0 siblings, 1 reply; 2+ messages in thread
From: Andrea Righi @ 2019-01-10 17:39 UTC (permalink / raw)
To: Steven Rostedt, Masami Hiramatsu; +Cc: Ingo Molnar, linux-kernel
It is possible to trigger a NULL pointer dereference by writing an
incorrectly formatted string to krpobe_events (omitting the symbol).
Example:
echo "r:event_1 " >> /sys/kernel/debug/tracing/kprobe_events
That triggers this:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
#PF error: [normal kernel read fault]
PGD 0 P4D 0
Oops: 0000 [#1] SMP PTI
CPU: 6 PID: 1757 Comm: bash Not tainted 5.0.0-rc1+ #125
Hardware name: Dell Inc. XPS 13 9370/0F6P3V, BIOS 1.5.1 08/09/2018
RIP: 0010:kstrtoull+0x2/0x20
Code: 28 00 00 00 75 17 48 83 c4 18 5b 41 5c 5d c3 b8 ea ff ff ff eb e1 b8 de ff ff ff eb da e8 d6 36 bb ff 66 0f 1f 44 00 00 31 c0 <80> 3f 2b 55 48 89 e5 0f 94 c0 48 01 c7 e8 5c ff ff ff 5d c3 66 2e
RSP: 0018:ffffb5d482e57cb8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff82b12720
RDX: ffffb5d482e57cf8 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffb5d482e57d70 R08: ffffa0c05e5a7080 R09: ffffa0c05e003980
R10: 0000000000000000 R11: 0000000040000000 R12: ffffa0c04fe87b08
R13: 0000000000000001 R14: 000000000000000b R15: ffffa0c058d749e1
FS: 00007f137c7f7740(0000) GS:ffffa0c05e580000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000497d46004 CR4: 00000000003606e0
Call Trace:
? trace_kprobe_create+0xb6/0x840
? _cond_resched+0x19/0x40
? _cond_resched+0x19/0x40
? __kmalloc+0x62/0x210
? argv_split+0x8f/0x140
? trace_kprobe_create+0x840/0x840
? trace_kprobe_create+0x840/0x840
create_or_delete_trace_kprobe+0x11/0x30
trace_run_command+0x50/0x90
trace_parse_run_command+0xc1/0x160
probes_write+0x10/0x20
__vfs_write+0x3a/0x1b0
? apparmor_file_permission+0x1a/0x20
? security_file_permission+0x31/0xf0
? _cond_resched+0x19/0x40
vfs_write+0xb1/0x1a0
ksys_write+0x55/0xc0
__x64_sys_write+0x1a/0x20
do_syscall_64+0x5a/0x120
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Fix by doing the proper argument check when a NULL symbol is passed in
trace_kprobe_create().
Signed-off-by: Andrea Righi <righi.andrea@gmail.com>
---
kernel/trace/trace_kprobe.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 5c19b8c41c7e..76410ceeff50 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -644,6 +644,8 @@ static int trace_kprobe_create(int argc, const char *argv[])
/* try to parse an address. if that fails, try to read the
* input as a symbol. */
+ if (!argv[1])
+ return -EINVAL;
if (kstrtoul(argv[1], 0, (unsigned long *)&addr)) {
/* Check whether uprobe event specified */
if (strchr(argv[1], '/') && strchr(argv[1], ':'))
--
2.17.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] tracing/kprobes: fix NULL pointer dereference in trace_kprobe_create()
2019-01-10 17:39 [PATCH] tracing/kprobes: fix NULL pointer dereference in trace_kprobe_create() Andrea Righi
@ 2019-01-11 0:51 ` Masami Hiramatsu
0 siblings, 0 replies; 2+ messages in thread
From: Masami Hiramatsu @ 2019-01-11 0:51 UTC (permalink / raw)
To: Andrea Righi; +Cc: Steven Rostedt, Ingo Molnar, linux-kernel
Hi Andrea,
On Thu, 10 Jan 2019 18:39:47 +0100
Andrea Righi <righi.andrea@gmail.com> wrote:
> It is possible to trigger a NULL pointer dereference by writing an
> incorrectly formatted string to krpobe_events (omitting the symbol).
>
> Example:
>
> echo "r:event_1 " >> /sys/kernel/debug/tracing/kprobe_events
>
> That triggers this:
>
> BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
> #PF error: [normal kernel read fault]
> PGD 0 P4D 0
> Oops: 0000 [#1] SMP PTI
> CPU: 6 PID: 1757 Comm: bash Not tainted 5.0.0-rc1+ #125
> Hardware name: Dell Inc. XPS 13 9370/0F6P3V, BIOS 1.5.1 08/09/2018
> RIP: 0010:kstrtoull+0x2/0x20
> Code: 28 00 00 00 75 17 48 83 c4 18 5b 41 5c 5d c3 b8 ea ff ff ff eb e1 b8 de ff ff ff eb da e8 d6 36 bb ff 66 0f 1f 44 00 00 31 c0 <80> 3f 2b 55 48 89 e5 0f 94 c0 48 01 c7 e8 5c ff ff ff 5d c3 66 2e
> RSP: 0018:ffffb5d482e57cb8 EFLAGS: 00010246
> RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff82b12720
> RDX: ffffb5d482e57cf8 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: ffffb5d482e57d70 R08: ffffa0c05e5a7080 R09: ffffa0c05e003980
> R10: 0000000000000000 R11: 0000000040000000 R12: ffffa0c04fe87b08
> R13: 0000000000000001 R14: 000000000000000b R15: ffffa0c058d749e1
> FS: 00007f137c7f7740(0000) GS:ffffa0c05e580000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000000 CR3: 0000000497d46004 CR4: 00000000003606e0
> Call Trace:
> ? trace_kprobe_create+0xb6/0x840
> ? _cond_resched+0x19/0x40
> ? _cond_resched+0x19/0x40
> ? __kmalloc+0x62/0x210
> ? argv_split+0x8f/0x140
> ? trace_kprobe_create+0x840/0x840
> ? trace_kprobe_create+0x840/0x840
> create_or_delete_trace_kprobe+0x11/0x30
> trace_run_command+0x50/0x90
> trace_parse_run_command+0xc1/0x160
> probes_write+0x10/0x20
> __vfs_write+0x3a/0x1b0
> ? apparmor_file_permission+0x1a/0x20
> ? security_file_permission+0x31/0xf0
> ? _cond_resched+0x19/0x40
> vfs_write+0xb1/0x1a0
> ksys_write+0x55/0xc0
> __x64_sys_write+0x1a/0x20
> do_syscall_64+0x5a/0x120
> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> Fix by doing the proper argument check when a NULL symbol is passed in
> trace_kprobe_create().
>
Oops! It is my fault on commit 6212dd29683e ("tracing/kprobes: Use dyn_event
framework for kprobe events")
Previously, we have following check, but it is removed
- if (argc < 2) {
- pr_info("Probe point is not specified.\n");
- return -EINVAL;
- }
and check it only for kprobe event but not kretprobe event.
/* argc must be >= 1 */
if (argv[0][0] == 'r') {
is_return = true;
flags |= TPARG_FL_RETURN;
} else if (argv[0][0] != 'p' || argc < 2)
return -ECANCELED;
I would like to recover above if block instead of adding new check.
Could you do it with Fixed: and Cc: stable@vger.kernel.org tags?
Thank you,
> Signed-off-by: Andrea Righi <righi.andrea@gmail.com>
> ---
> kernel/trace/trace_kprobe.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index 5c19b8c41c7e..76410ceeff50 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -644,6 +644,8 @@ static int trace_kprobe_create(int argc, const char *argv[])
>
> /* try to parse an address. if that fails, try to read the
> * input as a symbol. */
> + if (!argv[1])
> + return -EINVAL;
> if (kstrtoul(argv[1], 0, (unsigned long *)&addr)) {
> /* Check whether uprobe event specified */
> if (strchr(argv[1], '/') && strchr(argv[1], ':'))
> --
> 2.17.1
>
--
Masami Hiramatsu <mhiramat@kernel.org>
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2019-01-11 0:51 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-01-10 17:39 [PATCH] tracing/kprobes: fix NULL pointer dereference in trace_kprobe_create() Andrea Righi
2019-01-11 0:51 ` Masami Hiramatsu
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).