There's a fix for this already in the for-next branch:
https://github.com/btrfs/linux/commit/1a287050962c6847fa4918d6b2a0f4cee35c6943
On 17/12/24 22:58, Mirsad Todorovac wrote:
> >
> The static analyser tool gave the following advice:
>
> ./fs/btrfs/ioctl.c:4987:9-16: WARNING opportunity for kmemdup
>
> 4986 if (!iov) {
> → 4987 iov = kmalloc(sizeof(struct iovec) *
> args.iovcnt, GFP_NOFS);
> 4988 if (!iov) {
> 4989 unlock_extent(io_tree, start,
> lockend, &cached_state);
> 4990 btrfs_inode_unlock(inode,
> BTRFS_ILOCK_SHARED);
> 4991 ret = -ENOMEM;
> 4992 goto out_acct;
> 4993 }
> 4994
> → 4995 memcpy(iov, iovstack, sizeof(struct iovec) *
> args.iovcnt);
> 4996 }
>
> Replacing kmalloc() + memcpy() with kmemdump() doesn't change semantics.
> Original code works without fault, so this is not a bug fix but proposed
> improvement.
>
> Link:
> https://urldefense.com/v3/__https://lwn.net/Articles/198928/__;!!Bt8RZUm9aw!4OVzQmIUbyH-UGdUwMAL582hR4Q-7HN2fn9IpyxeA1T8qrcC8RdBVz4xuL4m35_kksUllAi6OmdbRehcFpwfHw$
> Fixes: 34310c442e175 ("btrfs: add io_uring command for encoded reads
> (ENCODED_READ ioctl)")
> Cc: Chris Mason <[email protected]>
> Cc: Josef Bacik <[email protected]>
> Cc: David Sterba <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Signed-off-by: Mirsad Todorovac <[email protected]>
> ---
> v1:
> initial version.
>
> fs/btrfs/ioctl.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 3af8bb0c8d75..c2f769334d3c 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -4984,15 +4984,13 @@ static int btrfs_uring_encoded_read(struct
> io_uring_cmd *cmd, unsigned int issue
> * undo this.
> */
> if (!iov) {
> - iov = kmalloc(sizeof(struct iovec) * args.iovcnt,
> GFP_NOFS);
> + iov = kmemdup(iovstack, sizeof(struct iovec) *
> args.iovcnt, GFP_NOFS);
> if (!iov) {
> unlock_extent(io_tree, start, lockend,
> &cached_state);
> btrfs_inode_unlock(inode, BTRFS_ILOCK_SHARED);
> ret = -ENOMEM;
> goto out_acct;
> }
> -
> - memcpy(iov, iovstack, sizeof(struct iovec) *
> args.iovcnt);
> }
>
> count = min_t(u64, iov_iter_count(&iter), disk_io_size);
