2023-05-23 13:06:21

by David Howells

Subject: [PATCH v2] cifs: Fix cifs_limit_bvec_subset() to correctly check the maxmimum size

Fix cifs_limit_bvec_subset() so that it limits the span to the maximum
specified and won't return with a size greater than max_size.

Fixes: d08089f649a0 ("cifs: Change the I/O paths to use an iterator rather than a page list")
Reported-by: Shyam Prasad N <[email protected]>
Signed-off-by: David Howells <[email protected]>
cc: Steve French <[email protected]>
cc: Rohith Surabattula <[email protected]>
cc: Paulo Alcantara <[email protected]>
cc: Tom Talpey <[email protected]>
cc: Jeff Layton <[email protected]>
cc: [email protected]
cc: [email protected]
---
fs/cifs/file.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index ba7f2e09d6c8..df88b8c04d03 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -3353,9 +3353,10 @@ static size_t cifs_limit_bvec_subset(const struct iov_iter *iter, size_t max_siz
while (n && ix < nbv) {
len = min3(n, bvecs[ix].bv_len - skip, max_size);
span += len;
+ max_size -= len;
nsegs++;
ix++;
- if (span >= max_size || nsegs >= max_segs)
+ if (max_size == 0 || nsegs >= max_segs)
break;
skip = 0;
n -= len;

2023-05-23 16:57:14

by Shyam Prasad N

Subject: Re: [PATCH v2] cifs: Fix cifs_limit_bvec_subset() to correctly check the maxmimum size

On Tue, May 23, 2023 at 6:24 PM David Howells <[email protected]> wrote:
>
> Fix cifs_limit_bvec_subset() so that it limits the span to the maximum
> specified and won't return with a size greater than max_size.
>
> Fixes: d08089f649a0 ("cifs: Change the I/O paths to use an iterator rather than a page list")
> Reported-by: Shyam Prasad N <[email protected]>
> Signed-off-by: David Howells <[email protected]>
> cc: Steve French <[email protected]>
> cc: Rohith Surabattula <[email protected]>
> cc: Paulo Alcantara <[email protected]>
> cc: Tom Talpey <[email protected]>
> cc: Jeff Layton <[email protected]>
> cc: [email protected]
> cc: [email protected]
> ---
> fs/cifs/file.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
> index ba7f2e09d6c8..df88b8c04d03 100644
> --- a/fs/cifs/file.c
> +++ b/fs/cifs/file.c
> @@ -3353,9 +3353,10 @@ static size_t cifs_limit_bvec_subset(const struct iov_iter *iter, size_t max_siz
> while (n && ix < nbv) {
> len = min3(n, bvecs[ix].bv_len - skip, max_size);
> span += len;
> + max_size -= len;
> nsegs++;
> ix++;
> - if (span >= max_size || nsegs >= max_segs)
> + if (max_size == 0 || nsegs >= max_segs)
> break;
> skip = 0;
> n -= len;
>

Looks good to me.

--
Regards,
Shyam