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tracing/kprobes: Fix NULL pointer dereference in trace_kprobe_create()
author
Andrea Righi
<righi.andrea@gmail.com>
Fri, 11 Jan 2019 06:01:13 +0000
(07:01 +0100)
committer
Steven Rostedt (VMware)
<rostedt@goodmis.org>
Tue, 15 Jan 2019 16:33:45 +0000
(11:33 -0500)
It is possible to trigger a NULL pointer dereference by writing an
incorrectly formatted string to krpobe_events (trying to create a
kretprobe 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 checks in trace_kprobe_create().
Cc: Ingo Molnar <mingo@redhat.com>
Link:
https://lore.kernel.org/lkml/20190111095108.b79a2ee026185cbd62365977@kernel.org
Link:
http://lkml.kernel.org/r/20190111060113.GA22841@xps-13
Fixes:
6212dd29683e
("tracing/kprobes: Use dyn_event framework for kprobe events")
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Andrea Righi <righi.andrea@gmail.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
kernel/trace/trace_kprobe.c
patch
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blob
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diff --git
a/kernel/trace/trace_kprobe.c
b/kernel/trace/trace_kprobe.c
index
5c19b8c
..
d5fb09e
100644
(file)
--- a/
kernel/trace/trace_kprobe.c
+++ b/
kernel/trace/trace_kprobe.c
@@
-607,11
+607,17
@@
static int trace_kprobe_create(int argc, const char *argv[])
char buf[MAX_EVENT_NAME_LEN];
unsigned int flags = TPARG_FL_KERNEL;
- /* argc must be >= 1 */
- if (argv[0][0] == 'r') {
+ switch (argv[0][0]) {
+ case 'r':
is_return = true;
flags |= TPARG_FL_RETURN;
- } else if (argv[0][0] != 'p' || argc < 2)
+ break;
+ case 'p':
+ break;
+ default:
+ return -ECANCELED;
+ }
+ if (argc < 2)
return -ECANCELED;
event = strchr(&argv[0][1], ':');