In the Linux kernel, the following vulnerability has been resolved:
uprobe: avoid out-of-bounds memory access of fetching args
Uprobe needs to fetch args into a percpu buffer, and then copy to ring
buffer to avoid non-atomic context problem.
Sometimes user-space strings, arrays can be very large, but the size of
percpu buffer is only page size. And store_trace_args() won't check
whether these data exceeds a single page or not, caused out-of-bounds
memory access.
It could be reproduced by following steps:
1. build kernel with CONFIG_KASAN enabled
2. save follow program as test.c
```
\#include <stdio.h>
\#include <stdlib.h>
\#include <string.h>
// If string length large than MAX_STRING_SIZE, the fetch_store_strlen()
// will return 0, cause __get_data_size() return shorter size, and
// store_trace_args() will not trigger out-of-bounds access.
// So make string length less than 4096.
\#define STRLEN 4093
void generate_string(char *str, int n)
{
int i;
for (i = 0; i < n; ++i)
{
char c = i % 26 + 'a';
str[i] = c;
}
str[n-1] = '\0';
}
void print_string(char *str)
{
printf("%s\n", str);
}
int main()
{
char tmp[STRLEN];
generate_string(tmp, STRLEN);
print_string(tmp);
return 0;
}
```
3. compile program
`gcc -o test test.c`
4. get the offset of `print_string()`
```
objdump -t test | grep -w print_string
0000000000401199 g F .text 000000000000001b print_string
```
5. configure uprobe with offset 0x1199
```
off=0x1199
cd /sys/kernel/debug/tracing/
echo "p /root/test:${off} arg1=+0(%di):ustring arg2=\$comm arg3=+0(%di):ustring"
> uprobe_events
echo 1 > events/uprobes/enable
echo 1 > tracing_on
```
6. run `test`, and kasan will report error.
==================================================================
BUG: KASAN: use-after-free in strncpy_from_user+0x1d6/0x1f0
Write of size 8 at addr ffff88812311c004 by task test/499CPU: 0 UID: 0 PID: 499 Comm: test Not tainted 6.12.0-rc3+ #18
Hardware name: Red Hat KVM, BIOS 1.16.0-4.al8 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x55/0x70
print_address_description.constprop.0+0x27/0x310
kasan_report+0x10f/0x120
? strncpy_from_user+0x1d6/0x1f0
strncpy_from_user+0x1d6/0x1f0
? rmqueue.constprop.0+0x70d/0x2ad0
process_fetch_insn+0xb26/0x1470
? __pfx_process_fetch_insn+0x10/0x10
? _raw_spin_lock+0x85/0xe0
? __pfx__raw_spin_lock+0x10/0x10
? __pte_offset_map+0x1f/0x2d0
? unwind_next_frame+0xc5f/0x1f80
? arch_stack_walk+0x68/0xf0
? is_bpf_text_address+0x23/0x30
? kernel_text_address.part.0+0xbb/0xd0
? __kernel_text_address+0x66/0xb0
? unwind_get_return_address+0x5e/0xa0
? __pfx_stack_trace_consume_entry+0x10/0x10
? arch_stack_walk+0xa2/0xf0
? _raw_spin_lock_irqsave+0x8b/0xf0
? __pfx__raw_spin_lock_irqsave+0x10/0x10
? depot_alloc_stack+0x4c/0x1f0
? _raw_spin_unlock_irqrestore+0xe/0x30
? stack_depot_save_flags+0x35d/0x4f0
? kasan_save_stack+0x34/0x50
? kasan_save_stack+0x24/0x50
? mutex_lock+0x91/0xe0
? __pfx_mutex_lock+0x10/0x10
prepare_uprobe_buffer.part.0+0x2cd/0x500
uprobe_dispatcher+0x2c3/0x6a0
? __pfx_uprobe_dispatcher+0x10/0x10
? __kasan_slab_alloc+0x4d/0x90
handler_chain+0xdd/0x3e0
handle_swbp+0x26e/0x3d0
? __pfx_handle_swbp+0x10/0x10
? uprobe_pre_sstep_notifier+0x151/0x1b0
irqentry_exit_to_user_mode+0xe2/0x1b0
asm_exc_int3+0x39/0x40
RIP: 0033:0x401199
Code: 01 c2 0f b6 45 fb 88 02 83 45 fc 01 8b 45 fc 3b 45 e4 7c b7 8b 45 e4 48 98 48 8d 50 ff 48 8b 45 e8 48 01 d0 ce
RSP: 002b:00007ffdf00576a8 EFLAGS: 00000206
RAX: 00007ffdf00576b0 RBX: 0000000000000000 RCX: 0000000000000ff2
RDX: 0000000000000ffc RSI: 0000000000000ffd RDI: 00007ffdf00576b0
RBP: 00007ffdf00586b0 R08: 00007feb2f9c0d20 R09: 00007feb2f9c0d20
R10: 0000000000000001 R11: 0000000000000202 R12: 0000000000401040
R13: 00007ffdf0058780 R14: 0000000000000000 R15: 0000000000000000
</TASK>
This commit enforces the buffer's maxlen less than a page-size to avoid
store_trace_args() out-of-memory access.
Metrics
Affected Vendors & Products
References
History
Mon, 04 Nov 2024 19:00:00 +0000
Type | Values Removed | Values Added |
---|---|---|
CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
Mon, 04 Nov 2024 11:30:00 +0000
Type | Values Removed | Values Added |
---|---|---|
References |
|
Tue, 29 Oct 2024 17:00:00 +0000
Type | Values Removed | Values Added |
---|---|---|
First Time appeared |
Linux
Linux linux Kernel |
|
Weaknesses | CWE-787 | |
CPEs | cpe:2.3:a:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.12:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.12:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.12:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.12:rc4:*:*:*:*:*:* |
|
Vendors & Products |
Linux
Linux linux Kernel |
|
Metrics |
cvssV3_1
|
cvssV3_1
|
Tue, 29 Oct 2024 01:45:00 +0000
Type | Values Removed | Values Added |
---|---|---|
References |
| |
Metrics |
threat_severity
|
cvssV3_1
|
Mon, 28 Oct 2024 01:15:00 +0000
Type | Values Removed | Values Added |
---|---|---|
Description | In the Linux kernel, the following vulnerability has been resolved: uprobe: avoid out-of-bounds memory access of fetching args Uprobe needs to fetch args into a percpu buffer, and then copy to ring buffer to avoid non-atomic context problem. Sometimes user-space strings, arrays can be very large, but the size of percpu buffer is only page size. And store_trace_args() won't check whether these data exceeds a single page or not, caused out-of-bounds memory access. It could be reproduced by following steps: 1. build kernel with CONFIG_KASAN enabled 2. save follow program as test.c ``` \#include <stdio.h> \#include <stdlib.h> \#include <string.h> // If string length large than MAX_STRING_SIZE, the fetch_store_strlen() // will return 0, cause __get_data_size() return shorter size, and // store_trace_args() will not trigger out-of-bounds access. // So make string length less than 4096. \#define STRLEN 4093 void generate_string(char *str, int n) { int i; for (i = 0; i < n; ++i) { char c = i % 26 + 'a'; str[i] = c; } str[n-1] = '\0'; } void print_string(char *str) { printf("%s\n", str); } int main() { char tmp[STRLEN]; generate_string(tmp, STRLEN); print_string(tmp); return 0; } ``` 3. compile program `gcc -o test test.c` 4. get the offset of `print_string()` ``` objdump -t test | grep -w print_string 0000000000401199 g F .text 000000000000001b print_string ``` 5. configure uprobe with offset 0x1199 ``` off=0x1199 cd /sys/kernel/debug/tracing/ echo "p /root/test:${off} arg1=+0(%di):ustring arg2=\$comm arg3=+0(%di):ustring" > uprobe_events echo 1 > events/uprobes/enable echo 1 > tracing_on ``` 6. run `test`, and kasan will report error. ================================================================== BUG: KASAN: use-after-free in strncpy_from_user+0x1d6/0x1f0 Write of size 8 at addr ffff88812311c004 by task test/499CPU: 0 UID: 0 PID: 499 Comm: test Not tainted 6.12.0-rc3+ #18 Hardware name: Red Hat KVM, BIOS 1.16.0-4.al8 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x55/0x70 print_address_description.constprop.0+0x27/0x310 kasan_report+0x10f/0x120 ? strncpy_from_user+0x1d6/0x1f0 strncpy_from_user+0x1d6/0x1f0 ? rmqueue.constprop.0+0x70d/0x2ad0 process_fetch_insn+0xb26/0x1470 ? __pfx_process_fetch_insn+0x10/0x10 ? _raw_spin_lock+0x85/0xe0 ? __pfx__raw_spin_lock+0x10/0x10 ? __pte_offset_map+0x1f/0x2d0 ? unwind_next_frame+0xc5f/0x1f80 ? arch_stack_walk+0x68/0xf0 ? is_bpf_text_address+0x23/0x30 ? kernel_text_address.part.0+0xbb/0xd0 ? __kernel_text_address+0x66/0xb0 ? unwind_get_return_address+0x5e/0xa0 ? __pfx_stack_trace_consume_entry+0x10/0x10 ? arch_stack_walk+0xa2/0xf0 ? _raw_spin_lock_irqsave+0x8b/0xf0 ? __pfx__raw_spin_lock_irqsave+0x10/0x10 ? depot_alloc_stack+0x4c/0x1f0 ? _raw_spin_unlock_irqrestore+0xe/0x30 ? stack_depot_save_flags+0x35d/0x4f0 ? kasan_save_stack+0x34/0x50 ? kasan_save_stack+0x24/0x50 ? mutex_lock+0x91/0xe0 ? __pfx_mutex_lock+0x10/0x10 prepare_uprobe_buffer.part.0+0x2cd/0x500 uprobe_dispatcher+0x2c3/0x6a0 ? __pfx_uprobe_dispatcher+0x10/0x10 ? __kasan_slab_alloc+0x4d/0x90 handler_chain+0xdd/0x3e0 handle_swbp+0x26e/0x3d0 ? __pfx_handle_swbp+0x10/0x10 ? uprobe_pre_sstep_notifier+0x151/0x1b0 irqentry_exit_to_user_mode+0xe2/0x1b0 asm_exc_int3+0x39/0x40 RIP: 0033:0x401199 Code: 01 c2 0f b6 45 fb 88 02 83 45 fc 01 8b 45 fc 3b 45 e4 7c b7 8b 45 e4 48 98 48 8d 50 ff 48 8b 45 e8 48 01 d0 ce RSP: 002b:00007ffdf00576a8 EFLAGS: 00000206 RAX: 00007ffdf00576b0 RBX: 0000000000000000 RCX: 0000000000000ff2 RDX: 0000000000000ffc RSI: 0000000000000ffd RDI: 00007ffdf00576b0 RBP: 00007ffdf00586b0 R08: 00007feb2f9c0d20 R09: 00007feb2f9c0d20 R10: 0000000000000001 R11: 0000000000000202 R12: 0000000000401040 R13: 00007ffdf0058780 R14: 0000000000000000 R15: 0000000000000000 </TASK> This commit enforces the buffer's maxlen less than a page-size to avoid store_trace_args() out-of-memory access. | |
Title | uprobe: avoid out-of-bounds memory access of fetching args | |
References |
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published: 2024-10-28T00:57:05.734Z
Updated: 2024-11-05T09:54:24.264Z
Reserved: 2024-10-21T19:36:19.939Z
Link: CVE-2024-50067
Vulnrichment
No data.
NVD
Status : Analyzed
Published: 2024-10-28T01:15:02.930
Modified: 2024-11-04T18:34:01.667
Link: CVE-2024-50067
Redhat