+ squashfs-fix-buffer-release-race-condition-in-readahead-code.patch added to mm-hotfixes-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: squashfs: fix buffer release race condition in readahead code
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     squashfs-fix-buffer-release-race-condition-in-readahead-code.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/squashfs-fix-buffer-release-race-condition-in-readahead-code.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Phillip Lougher <phillip@squashfs.org.uk>
Subject: squashfs: fix buffer release race condition in readahead code
Date: Thu, 20 Oct 2022 23:36:16 +0100

Fix a buffer release race condition, where the error value was used after
release.

Link: https://lkml.kernel.org/r/20221020223616.7571-4-phillip@squashfs.org.uk
Fixes: b09a7a036d20 ("squashfs: support reading fragments in readahead call")
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Cc: <stable@vger.kernel.org>
Cc: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: Dimitri John Ledkov <dimitri.ledkov@canonical.com>
Cc: Hsin-Yi Wang <hsinyi@chromium.org>
Cc: Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr>
Cc: Slade Watkins <srw@sladewatkins.net>
Cc: Thorsten Leemhuis <regressions@leemhuis.info>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/squashfs/file.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/fs/squashfs/file.c~squashfs-fix-buffer-release-race-condition-in-readahead-code
+++ a/fs/squashfs/file.c
@@ -506,8 +506,9 @@ static int squashfs_readahead_fragment(s
 		squashfs_i(inode)->fragment_size);
 	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
 	unsigned int n, mask = (1 << (msblk->block_log - PAGE_SHIFT)) - 1;
+	int error = buffer->error;
 
-	if (buffer->error)
+	if (error)
 		goto out;
 
 	expected += squashfs_i(inode)->fragment_offset;
@@ -529,7 +530,7 @@ static int squashfs_readahead_fragment(s
 
 out:
 	squashfs_cache_put(buffer);
-	return buffer->error;
+	return error;
 }
 
 static void squashfs_readahead(struct readahead_control *ractl)
_

Patches currently in -mm which might be from phillip@squashfs.org.uk are

squashfs-fix-read-regression-introduced-in-readahead-code.patch
squashfs-fix-extending-readahead-beyond-end-of-file.patch
squashfs-fix-buffer-release-race-condition-in-readahead-code.patch