From: Ian Bridges Date: Mon, 1 Jun 2026 18:44:33 +0000 (-0500) Subject: ocfs2: fix out-of-bounds write in ocfs2_remove_refcount_extent X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=1ec3cca2d8b6b9ff6584ca626d4c8918bbf48d44;p=thirdparty%2Fkernel%2Flinux.git ocfs2: fix out-of-bounds write in ocfs2_remove_refcount_extent [BUG] Unlinking a refcounted file whose refcount tree has leaf blocks triggers a fortify panic due to an out-of-bounds write. [CAUSE] When the last leaf block is removed from a refcount tree, ocfs2_remove_refcount_extent() converts the root back to leaf mode with a bulk memset on &rb->rf_records. rf_records sits in an anonymous union with rf_list. rf_list.l_tree_depth aliases rf_records.rl_count, and is 0 for a single-level tree. With rl_count equal to 0, the memset writes past the 16-byte declared size of rf_records, which the fortify checker catches. [FIX] Replace the bulk memset on &rb->rf_records with a correctly-bounded memset on rl_recs[] alone, after setting rl_count to the correct value. Link: https://lore.kernel.org/ah3TESOsEO9j_JLU@dev Fixes: 2f26f58df041 ("ocfs2: annotate flexible array members with __counted_by_le()") Signed-off-by: Ian Bridges Reported-by: syzbot+3ef989aae096b30f1663@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3ef989aae096b30f1663 Reviewed-by: Joseph Qi Cc: Mark Fasheh Cc: Joel Becker Cc: Junxiao Bi Cc: Changwei Ge Cc: Jun Piao Cc: Heming Zhao Signed-off-by: Andrew Morton --- diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c index 8eee5be4d1ed..7323bde70caa 100644 --- a/fs/ocfs2/refcounttree.c +++ b/fs/ocfs2/refcounttree.c @@ -2131,10 +2131,15 @@ static int ocfs2_remove_refcount_extent(handle_t *handle, rb->rf_flags = 0; rb->rf_parent = 0; rb->rf_cpos = 0; - memset(&rb->rf_records, 0, sb->s_blocksize - - offsetof(struct ocfs2_refcount_block, rf_records)); + rb->rf_records.rl_used = 0; + rb->rf_records.rl_reserved2 = 0; + rb->rf_records.rl_reserved1 = 0; + /* rl_count determines the memset size and fortify object size. */ rb->rf_records.rl_count = cpu_to_le16(ocfs2_refcount_recs_per_rb(sb)); + memset(rb->rf_records.rl_recs, 0, + le16_to_cpu(rb->rf_records.rl_count) * + sizeof(*rb->rf_records.rl_recs)); } ocfs2_journal_dirty(handle, ref_root_bh);