From a63308ab426f3a3c7e33b02c150ea59054620261 Mon Sep 17 00:00:00 2001 From: Zhan Xusheng Date: Thu, 6 Aug 2026 10:20:44 +0800 Subject: [PATCH] ocfs2: fix readdir position truncation on 32-bit kernels 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 Fixes: ccd979bdbce9 ("[PATCH] OCFS2: The Second Oracle Cluster Filesystem") Signed-off-by: Zhan Xusheng Reviewed-by: Joseph Qi Cc: Mark Fasheh Cc: Joel Becker Cc: Junxiao Bi Cc: Changwei Ge Cc: Jun Piao Cc: Heming Zhao Cc: Andreas Dilger Cc: Jan Kara Cc: Ojaswin Mujoo Cc: "Ritesh Harjani (IBM)" Cc: Ted Ts'o Cc: "zhangyi (F)" Cc: Signed-off-by: Andrew Morton --- fs/ocfs2/dir.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/ocfs2/dir.c b/fs/ocfs2/dir.c index 7e09a5a4d49e..5148a9d6e1c4 100644 --- a/fs/ocfs2/dir.c +++ b/fs/ocfs2/dir.c @@ -1959,7 +1959,7 @@ static int ocfs2_dir_foreach_blk_el(struct inode *inode, 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); }