[PATCH v2] io_uring: fix filename leak in __io_openat_prep()

[PATCH v2] io_uring: fix filename leak in __io_openat_prep()

[Prithvi Tambewagh]

 __io_openat_prep() allocates a struct filename using getname(). However,
for the condition of the file being installed in the fixed file table as
well as having O_CLOEXEC flag set, the function returns early. At that
point, the request doesn't have REQ_F_NEED_CLEANUP flag set. Due to this,
the memory for the newly allocated struct filename is not cleaned up,
causing a memory leak.

Fix this by setting the REQ_F_NEED_CLEANUP for the request just after the
successful getname() call, so that when the request is torn down, the
filename will be cleaned up, along with other resources needing cleanup.

Reported-by: syzbot+00e61c43eb5e4740438f@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=00e61c43eb5e4740438f
Tested-by: syzbot+00e61c43eb5e4740438f@syzkaller.appspotmail.com
Cc: stable@vger.kernel.org
Signed-off-by: Prithvi Tambewagh <activprithvi@gmail.com>
---
 io_uring/openclose.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/io_uring/openclose.c b/io_uring/openclose.c
index bfeb91b31bba..15dde9bd6ff6 100644
--- a/io_uring/openclose.c
+++ b/io_uring/openclose.c
@@ -73,13 +73,13 @@ static int __io_openat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe
 		open->filename = NULL;
 		return ret;
 	}
+	req->flags |= REQ_F_NEED_CLEANUP;
 
 	open->file_slot = READ_ONCE(sqe->file_index);
 	if (open->file_slot && (open->how.flags & O_CLOEXEC))
 		return -EINVAL;
 
 	open->nofile = rlimit(RLIMIT_NOFILE);
-	req->flags |= REQ_F_NEED_CLEANUP;
 	if (io_openat_force_async(open))
 		req->flags |= REQ_F_FORCE_ASYNC;
 	return 0;

base-commit: b927546677c876e26eba308550207c2ddf812a43
-- 
2.34.1

Re: [PATCH v2] io_uring: fix filename leak in __io_openat_prep()

[Jens Axboe]

On 12/25/25 12:28 AM, Prithvi Tambewagh wrote:
>  __io_openat_prep() allocates a struct filename using getname(). However,
> for the condition of the file being installed in the fixed file table as
> well as having O_CLOEXEC flag set, the function returns early. At that
> point, the request doesn't have REQ_F_NEED_CLEANUP flag set. Due to this,
> the memory for the newly allocated struct filename is not cleaned up,
> causing a memory leak.
> 
> Fix this by setting the REQ_F_NEED_CLEANUP for the request just after the
> successful getname() call, so that when the request is torn down, the
> filename will be cleaned up, along with other resources needing cleanup.
> 
> Reported-by: syzbot+00e61c43eb5e4740438f@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=00e61c43eb5e4740438f
> Tested-by: syzbot+00e61c43eb5e4740438f@syzkaller.appspotmail.com
> Cc: stable@vger.kernel.org
> Signed-off-by: Prithvi Tambewagh <activprithvi@gmail.com>

Thanks, just missing a:

Fixes: b9445598d8c6 ("io_uring: openat directly into fixed fd table")

which I'll add when applying.

-- 
Jens Axboe

Re: [PATCH v2] io_uring: fix filename leak in __io_openat_prep()

[Jens Axboe]

On Thu, 25 Dec 2025 12:58:29 +0530, Prithvi Tambewagh wrote:
>  __io_openat_prep() allocates a struct filename using getname(). However,
> for the condition of the file being installed in the fixed file table as
> well as having O_CLOEXEC flag set, the function returns early. At that
> point, the request doesn't have REQ_F_NEED_CLEANUP flag set. Due to this,
> the memory for the newly allocated struct filename is not cleaned up,
> causing a memory leak.
> 
> [...]

Applied, thanks!

[1/1] io_uring: fix filename leak in __io_openat_prep()
      commit: b14fad555302a2104948feaff70503b64c80ac01

Best regards,
-- 
Jens Axboe

Re: [PATCH v2] io_uring: fix filename leak in __io_openat_prep()

[Prithvi]

On Thu, Dec 25, 2025 at 08:08:50AM -0700, Jens Axboe wrote:
> 
> On Thu, 25 Dec 2025 12:58:29 +0530, Prithvi Tambewagh wrote:
> >  __io_openat_prep() allocates a struct filename using getname(). However,
> > for the condition of the file being installed in the fixed file table as
> > well as having O_CLOEXEC flag set, the function returns early. At that
> > point, the request doesn't have REQ_F_NEED_CLEANUP flag set. Due to this,
> > the memory for the newly allocated struct filename is not cleaned up,
> > causing a memory leak.
> > 
> > [...]
> 
> Applied, thanks!
> 
> [1/1] io_uring: fix filename leak in __io_openat_prep()
>       commit: b14fad555302a2104948feaff70503b64c80ac01
> 
> Best regards,
> -- 
> Jens Axboe
> 
> 
> 

Thank you!

Best Regards,
Prithvi