[PATCH] blk-trace: Fix potential buffer overflow in blk_trace_setup()

[PATCH] blk-trace: Fix potential buffer overflow in blk_trace_setup()

[Huiwen He]

The legacy struct blk_user_trace_setup has a 32-byte name field,
while buts2->name is a 64-byte buffer (BLKTRACE_BDEV_SIZE2).

Since commit 113cbd62824a ("blktrace: pass blk_user_trace2 to setup
functions"), blk_trace_setup() copied buts2->name into buts->name
using strcpy(). strcpy() performs no bounds checking on the destination
buffer, which can overflow if the source string exceeds 31 characters.

Replace deprecated [1] strcpy() with strscpy() to ensure proper bounds
checking and prevent potential buffer overflow.

Link: https://github.com/KSPP/linux/issues/88 [1]

Fixes: 113cbd62824a ("blktrace: pass blk_user_trace2 to setup functions")
Signed-off-by: Huiwen He <hehuiwen@kylinos.cn>
---
 kernel/trace/blktrace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index d031c8d80be4..50460e2e7212 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -793,7 +793,7 @@ int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 		return PTR_ERR(bt);
 	}
 	blk_trace_setup_finalize(q, name, 1, bt, &buts2);
-	strcpy(buts.name, buts2.name);
+	strscpy(buts.name, buts2.name);
 	mutex_unlock(&q->debugfs_mutex);
 
 	if (copy_to_user(arg, &buts, sizeof(buts))) {
-- 
2.25.1

Re: [PATCH] blk-trace: Fix potential buffer overflow in blk_trace_setup()

[Christoph Hellwig]

On Tue, Nov 25, 2025 at 04:24:20PM +0800, Huiwen He wrote:
> The legacy struct blk_user_trace_setup has a 32-byte name field,
> while buts2->name is a 64-byte buffer (BLKTRACE_BDEV_SIZE2).
> 
> Since commit 113cbd62824a ("blktrace: pass blk_user_trace2 to setup
> functions"), blk_trace_setup() copied buts2->name into buts->name
> using strcpy(). strcpy() performs no bounds checking on the destination
> buffer, which can overflow if the source string exceeds 31 characters.
> 
> Replace deprecated [1] strcpy() with strscpy() to ensure proper bounds
> checking and prevent potential buffer overflow.

At this point all this has been checked as part of the setup.  If you
hatr strcpy with passing, just doing a memcpy of BLKTRACE_BDEV_SIZE2
is the saner alternative.