On Sat, Nov 09, 2024 at 08:40:30PM +0800, Kuan-Wei Chiu wrote:

Hi Jinjie,

On Thu, Oct 24, 2024 at 05:43:03PM +0800, Jinjie Ruan wrote:

...

In kunit_debugfs_create_suite(), if alloc_string_stream() fails in the kunit_suite_for_each_test_case() loop, the "suite->log = stream" has assigned before, and the error path only free the suite->log's stream memory but not set it to NULL in string_stream_destroy(), so the later string_stream_clear() of suite->log in kunit_init_suite() will cause below UAF bug.

Set stream pointer to NULL after free in string_stream_destroy() to fix it.

Unable to handle kernel paging request at virtual address 006440150000030d Mem abort info: ESR = 0x0000000096000004 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x04: level 0 translation fault Data abort info: ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000 CM = 0, WnR = 0, TnD = 0, TagAccess = 0 GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 [006440150000030d] address between user and kernel address ranges Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: iio_test_gts industrialio_gts_helper cfg80211 rfkill ipv6 [last unloaded: iio_test_gts] CPU: 5 UID: 0 PID: 6253 Comm: modprobe Tainted: G B W N 6.12.0-rc4+ #458 Tainted: [B]=BAD_PAGE, [W]=WARN, [N]=TEST Hardware name: linux,dummy-virt (DT) pstate: 40000005 (nZcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : string_stream_clear+0x54/0x1ac lr : string_stream_clear+0x1a8/0x1ac sp : ffffffc080b47410 x29: ffffffc080b47410 x28: 006440550000030d x27: ffffff80c96b5e98 x26: ffffff80c96b5e80 x25: ffffffe461b3f6c0 x24: 0000000000000003 x23: ffffff80c96b5e88 x22: 1ffffff019cdf4fc x21: dfffffc000000000 x20: ffffff80ce6fa7e0 x19: 032202a80000186d x18: 0000000000001840 x17: 0000000000000000 x16: 0000000000000000 x15: ffffffe45c355cb4 x14: ffffffe45c35589c x13: ffffffe45c03da78 x12: ffffffb810168e75 x11: 1ffffff810168e74 x10: ffffffb810168e74 x9 : dfffffc000000000 x8 : 0000000000000004 x7 : 0000000000000003 x6 : 0000000000000001 x5 : ffffffc080b473a0 x4 : 0000000000000000 x3 : 0000000000000000 x2 : 0000000000000001 x1 : ffffffe462fbf620 x0 : dfffffc000000000 Call trace: string_stream_clear+0x54/0x1ac __kunit_test_suites_init+0x108/0x1d8 kunit_exec_run_tests+0xb8/0x100 kunit_module_notify+0x400/0x55c notifier_call_chain+0xfc/0x3b4 blocking_notifier_call_chain+0x68/0x9c do_init_module+0x24c/0x5c8 load_module+0x4acc/0x4e90 init_module_from_file+0xd4/0x128 idempotent_init_module+0x2d4/0x57c __arm64_sys_finit_module+0xac/0x100 invoke_syscall+0x6c/0x258 el0_svc_common.constprop.0+0x160/0x22c do_el0_svc+0x44/0x5c el0_svc+0x48/0xb8 el0t_64_sync_handler+0x13c/0x158 el0t_64_sync+0x190/0x194 Code: f9400753 d2dff800 f2fbffe0 d343fe7c (38e06b80) ---[ end trace 0000000000000000 ]--- Kernel panic - not syncing: Oops: Fatal exception

Cc: stable@vger.kernel.org Fixes: a3fdf784780c ("kunit: string-stream: Decouple string_stream from kunit") Signed-off-by: Jinjie Ruan ruanjinjie@huawei.com

---

lib/kunit/string-stream.c | 1 + 1 file changed, 1 insertion(+)

diff --git a/lib/kunit/string-stream.c b/lib/kunit/string-stream.c index 54f4fdcbfac8..00ad518b730b 100644 --- a/lib/kunit/string-stream.c +++ b/lib/kunit/string-stream.c @@ -178,6 +178,7 @@ void string_stream_destroy(struct string_stream *stream) string_stream_clear(stream); kfree(stream);

• stream = NULL;

Thanks for proposing the fix. However, I don't believe it fully resolves the UAF issue. Changing the stream pointer value within string_stream_destroy() doesn't update the caller's stream pointer, so the issue remains.

I think the correct approach would be to set the log pointer to NULL in the error path of kunit_debugfs_create_suite() to address the issue. Let me know if I've missed something or overlooked an obvious detail.

BTW, since alloc_string_stream() returns -ENOMEM on error rather than NULL, it's best for the caller to check it with IS_ERR() instead of IS_ERR_OR_NULL(). It's not a big issue, but I can send a cleanup patch later to address this.

Regards, Kuan-Wei

On 2024/11/9 20:40, Kuan-Wei Chiu wrote:

Hi Jinjie,

On Thu, Oct 24, 2024 at 05:43:03PM +0800, Jinjie Ruan wrote:

...

In kunit_debugfs_create_suite(), if alloc_string_stream() fails in the kunit_suite_for_each_test_case() loop, the "suite->log = stream" has assigned before, and the error path only free the suite->log's stream memory but not set it to NULL in string_stream_destroy(), so the later string_stream_clear() of suite->log in kunit_init_suite() will cause below UAF bug.

Set stream pointer to NULL after free in string_stream_destroy() to fix it.

Unable to handle kernel paging request at virtual address 006440150000030d Mem abort info: ESR = 0x0000000096000004 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x04: level 0 translation fault Data abort info: ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000 CM = 0, WnR = 0, TnD = 0, TagAccess = 0 GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 [006440150000030d] address between user and kernel address ranges Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: iio_test_gts industrialio_gts_helper cfg80211 rfkill ipv6 [last unloaded: iio_test_gts] CPU: 5 UID: 0 PID: 6253 Comm: modprobe Tainted: G B W N 6.12.0-rc4+ #458 Tainted: [B]=BAD_PAGE, [W]=WARN, [N]=TEST Hardware name: linux,dummy-virt (DT) pstate: 40000005 (nZcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : string_stream_clear+0x54/0x1ac lr : string_stream_clear+0x1a8/0x1ac sp : ffffffc080b47410 x29: ffffffc080b47410 x28: 006440550000030d x27: ffffff80c96b5e98 x26: ffffff80c96b5e80 x25: ffffffe461b3f6c0 x24: 0000000000000003 x23: ffffff80c96b5e88 x22: 1ffffff019cdf4fc x21: dfffffc000000000 x20: ffffff80ce6fa7e0 x19: 032202a80000186d x18: 0000000000001840 x17: 0000000000000000 x16: 0000000000000000 x15: ffffffe45c355cb4 x14: ffffffe45c35589c x13: ffffffe45c03da78 x12: ffffffb810168e75 x11: 1ffffff810168e74 x10: ffffffb810168e74 x9 : dfffffc000000000 x8 : 0000000000000004 x7 : 0000000000000003 x6 : 0000000000000001 x5 : ffffffc080b473a0 x4 : 0000000000000000 x3 : 0000000000000000 x2 : 0000000000000001 x1 : ffffffe462fbf620 x0 : dfffffc000000000 Call trace: string_stream_clear+0x54/0x1ac __kunit_test_suites_init+0x108/0x1d8 kunit_exec_run_tests+0xb8/0x100 kunit_module_notify+0x400/0x55c notifier_call_chain+0xfc/0x3b4 blocking_notifier_call_chain+0x68/0x9c do_init_module+0x24c/0x5c8 load_module+0x4acc/0x4e90 init_module_from_file+0xd4/0x128 idempotent_init_module+0x2d4/0x57c __arm64_sys_finit_module+0xac/0x100 invoke_syscall+0x6c/0x258 el0_svc_common.constprop.0+0x160/0x22c do_el0_svc+0x44/0x5c el0_svc+0x48/0xb8 el0t_64_sync_handler+0x13c/0x158 el0t_64_sync+0x190/0x194 Code: f9400753 d2dff800 f2fbffe0 d343fe7c (38e06b80) ---[ end trace 0000000000000000 ]--- Kernel panic - not syncing: Oops: Fatal exception

Cc: stable@vger.kernel.org Fixes: a3fdf784780c ("kunit: string-stream: Decouple string_stream from kunit") Signed-off-by: Jinjie Ruan ruanjinjie@huawei.com

---

lib/kunit/string-stream.c | 1 + 1 file changed, 1 insertion(+)

diff --git a/lib/kunit/string-stream.c b/lib/kunit/string-stream.c index 54f4fdcbfac8..00ad518b730b 100644 --- a/lib/kunit/string-stream.c +++ b/lib/kunit/string-stream.c @@ -178,6 +178,7 @@ void string_stream_destroy(struct string_stream *stream) string_stream_clear(stream); kfree(stream);

• stream = NULL;

Thanks for proposing the fix. However, I don't believe it fully resolves the UAF issue. Changing the stream pointer value within string_stream_destroy() doesn't update the caller's stream pointer, so the issue remains.

I think the correct approach would be to set the log pointer to NULL in the error path of kunit_debugfs_create_suite() to address the issue. Let me know if I've missed something or overlooked an obvious detail.

Here's the proposed code:

diff --git a/lib/kunit/debugfs.c b/lib/kunit/debugfs.c index d548750a325a..b25d214b93e1 100644 --- a/lib/kunit/debugfs.c +++ b/lib/kunit/debugfs.c @@ -212,8 +212,11 @@ void kunit_debugfs_create_suite(struct kunit_suite *suite)

err: string_stream_destroy(suite->log);

• kunit_suite_for_each_test_case(suite, test_case)

• suite->log = NULL;
• kunit_suite_for_each_test_case(suite, test_case) { string_stream_destroy(test_case->log);

• test_case->log = NULL;
  

• }

It looks fine, test it and if ok, will update it.

}

void kunit_debugfs_destroy_suite(struct kunit_suite *suite)

...

} static void resource_free_string_stream(void *p) -- 2.34.1