5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Zhan Xusheng <redacted>
commit a63308ab426f3a3c7e33b02c150ea59054620261 upstream.
In ocfs2_dir_foreach_blk_el(), the directory cookie position is
rebuilt with
ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1)) | offset;
`ctx->pos` is loff_t (signed 64-bit), while `sb->s_blocksize` is
unsigned long. On 32-bit kernels unsigned long is 32-bit, so the mask
~(sb->s_blocksize - 1)
is computed as a 32-bit unsigned value (e.g. 0xfffff000 for a 4 KiB
block size). In the AND expression with the 64-bit `ctx->pos`, that
unsigned operand is zero-extended to 64 bits per the usual arithmetic
conversions, yielding 0x00000000fffff000. The high 32 bits of
`ctx->pos` are silently cleared, even though directory size is
allowed to exceed 4 GiB.
When readdir() crosses the 4 GiB boundary on a 32-bit kernel the
position is reset back into the first 4 GiB block, making the
re-validation path re-enumerate already-returned dirents indefinitely.
This is ocfs2_dir_foreach_blk_el(), the extent-list readdir path taken
for all non-inline directories, so a directory large enough to cross
4 GiB reaches it.
This is the same class of bug that commit 3dce5bb82c97 ("exfat: Fix
bitwise operation having different size") fixed in exfat, and the
fix mirrors the equivalent ext4 fix in this series. Cast the operand
to loff_t so the mask is 64-bit before the AND:
ctx->pos = (ctx->pos & ~((loff_t)sb->s_blocksize - 1)) | offset;
64-bit kernels are unaffected.
Link: https://lore.kernel.org/20260806022044.167962-3-zhanxusheng@xiaomi.com (local)
Fixes: ccd979bdbce9 ("[PATCH] OCFS2: The Second Oracle Cluster Filesystem")
Signed-off-by: Zhan Xusheng <redacted>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <redacted>
Cc: Changwei Ge <redacted>
Cc: Jun Piao <redacted>
Cc: Heming Zhao <heming.zhao@suse.com>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Jan Kara <jack@suse.cz>
Cc: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Cc: "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>
Cc: Ted Ts'o <tytso@mit.edu>
Cc: "zhangyi (F)" <yi.zhang@huawei.com>
Cc: <redacted>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/ocfs2/dir.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/ocfs2/dir.c
+++ b/fs/ocfs2/dir.c
@@ -1882,7 +1882,7 @@ static int ocfs2_dir_foreach_blk_el(stru
i += le16_to_cpu(de->rec_len);
}
offset = i;
- ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1))
+ ctx->pos = (ctx->pos & ~((loff_t)sb->s_blocksize - 1))
| offset;
*f_version = inode_query_iversion(inode);
}