From 0cdc7dde00ec63ac714271fa8b2918d630b8da1a Mon Sep 17 00:00:00 2001 From: Ian Bridges Date: Thu, 23 Jul 2026 23:57:03 -0500 Subject: [PATCH] ocfs2: fix missing metadata reservation for large xattrs [BUG] lsetxattr() panics the kernel when setting a large xattr value on a fragmented filesystem where the file already has an external xattr block. [CAUSE] ocfs2_calc_xattr_set_need() never reserves metadata blocks for a new xattr value's extent tree when the file already has an external xattr block. The not_found path leaves meta_add at zero, so meta_ac is NULL when ocfs2_xattr_extend_allocation() runs. A new value root has room for a single extent record. On a fragmented filesystem, the allocator cannot satisfy the xattr value in one contiguous run, so each non-contiguous run requires its own extent record. When the value root's extent list is full and meta_ac is NULL, ocfs2_add_clusters_in_btree() returns RESTART_META, and ocfs2_xattr_extend_allocation() hits BUG_ON(why == RESTART_META). [FIX] The case where no xattr block exists yet already calls ocfs2_extend_meta_needed(&def_xv.xv.xr_list) to reserve value tree metadata. Add the same reservation to the case where an xattr block already exists, making the two cases consistent. Replace the BUG_ON with a -ENOSPC return so that if RESTART_META is returned despite the reservation, the error propagates to userspace instead of panicking the kernel. Link: https://lore.kernel.org/amLwn3i9tET8yhG7@dev Fixes: a78f9f466894 ("ocfs2: make xattr extension work with new local alloc reservation.") Signed-off-by: Ian Bridges Reported-by: syzbot+e538032956b1157914a3@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=e538032956b1157914a3 Reviewed-by: Joseph Qi Cc: Mark Fasheh Cc: Joel Becker Cc: Junxiao Bi Cc: Changwei Ge Cc: Jun Piao Cc: Heming Zhao Cc: Signed-off-by: Andrew Morton --- fs/ocfs2/xattr.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c index ed774bded974..94ae1fb83cf1 100644 --- a/fs/ocfs2/xattr.c +++ b/fs/ocfs2/xattr.c @@ -764,12 +764,10 @@ static int ocfs2_xattr_extend_allocation(struct inode *inode, prev_clusters; if (why != RESTART_NONE && clusters_to_add) { - /* - * We can only fail in case the alloc file doesn't give - * up enough clusters. - */ - BUG_ON(why == RESTART_META); - + if (why == RESTART_META) { + status = -ENOSPC; + break; + } credits = ocfs2_calc_extend_credits(inode->i_sb, &vb->vb_xv->xr_list); status = ocfs2_extend_trans(handle, credits); @@ -3443,6 +3441,14 @@ static int ocfs2_calc_xattr_set_need(struct inode *inode, } else credits += OCFS2_SUBALLOC_ALLOC + 1; + /* + * Reserve metadata for the new xattr's value extent tree. + * The not_found path above adds credits for this tree but + * omits meta_add, leaving meta_ac NULL for large values. + */ + if (xi->xi_value_len > OCFS2_XATTR_INLINE_SIZE) + meta_add += ocfs2_extend_meta_needed(&def_xv.xv.xr_list); + /* * This cluster will be used either for new bucket or for * new xattr block.