Re: [PATCH 5.15.y 5/6] filemap: Fix bounds checking in filemap_read()

[Sasha Levin <sashal@kernel.org>]

[ Sasha's backport helper bot ]

Hi,

✅ All tests passed successfully. No issues detected.
No action required from the submitter.

The upstream commit SHA1 provided is correct: ace149e0830c380ddfce7e466fe860ca502fe4ee

WARNING: Author mismatch between patch and upstream commit:
Backport author: Harshit Mogalapalli<harshit.m.mogalapalli@oracle.com>
Commit author: Trond Myklebust<trond.myklebust@hammerspace.com>

Status in newer kernel trees:
6.14.y | Present (exact SHA1)
6.13.y | Present (exact SHA1)
6.12.y | Present (exact SHA1)
6.6.y | Present (different SHA1: a2746ab3bbc9)
6.1.y | Present (different SHA1: 26530b757c81)

Note: The patch differs from the upstream commit:
---
1:  ace149e0830c3 ! 1:  dea76eb0a8d6e filemap: Fix bounds checking in filemap_read()
    @@ Metadata
      ## Commit message ##
         filemap: Fix bounds checking in filemap_read()
     
    +    [ Upstream commit ace149e0830c380ddfce7e466fe860ca502fe4ee ]
    +
         If the caller supplies an iocb->ki_pos value that is close to the
         filesystem upper limit, and an iterator with a count that causes us to
         overflow that limit, then filemap_read() enters an infinite loop.
    @@ Commit message
         Tested-by: Mike Snitzer <snitzer@kernel.org>
         Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
         Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    +    (cherry picked from commit ace149e0830c380ddfce7e466fe860ca502fe4ee)
    +    [Harshit: Minor conflict resolved due to missing commit: 25d6a23e8d28
    +    ("filemap: Convert filemap_get_read_batch() to use a folio_batch") in
    +    5.15.y]
    +    Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
     
      ## mm/filemap.c ##
     @@ mm/filemap.c: ssize_t filemap_read(struct kiocb *iocb, struct iov_iter *iter,
    @@ mm/filemap.c: ssize_t filemap_read(struct kiocb *iocb, struct iov_iter *iter,
      
     -	iov_iter_truncate(iter, inode->i_sb->s_maxbytes);
     +	iov_iter_truncate(iter, inode->i_sb->s_maxbytes - iocb->ki_pos);
    - 	folio_batch_init(&fbatch);
    + 	pagevec_init(&pvec);
      
      	do {
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-6.1.y        |  Success    |  Success   |