From a8e72879cd0d8422c0b47d6d3c1802274fe73b98 Mon Sep 17 00:00:00 2001 From: Yichong Chen Date: Wed, 8 Jul 2026 16:22:21 +0800 Subject: [PATCH] ovl: fix trusted xattr escape prefix matching In the trusted.* xattr namespace, ovl_is_escaped_xattr() compares one byte less than the escaped overlay xattr prefix length. This makes it match "trusted.overlay.overlay" without requiring the trailing dot. As a result, an xattr such as "trusted.overlay.overlayfoo" is incorrectly treated as an escaped overlay xattr. This can be reproduced by setting "trusted.overlay.overlayfoo" on a lower file and listing xattrs through an overlay mount. listxattr() then exposes it as "trusted.overlay.oo", and a following getxattr() on that listed name fails with ENODATA. Compare the full escaped prefix, including the trailing dot, so similarly-prefixed private xattrs are not misclassified. Fixes: dad02fad84cbc ("ovl: Support escaped overlay.* xattrs") Signed-off-by: Yichong Chen Link: https://patch.msgid.link/20260708082221.633602-1-chenyichong@uniontech.com Reviewed-by: Amir Goldstein Signed-off-by: Christian Brauner (Amutable) --- fs/overlayfs/xattrs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/overlayfs/xattrs.c b/fs/overlayfs/xattrs.c index aa95855c7023..859e80ae6f40 100644 --- a/fs/overlayfs/xattrs.c +++ b/fs/overlayfs/xattrs.c @@ -13,7 +13,7 @@ static bool ovl_is_escaped_xattr(struct super_block *sb, const char *name) OVL_XATTR_ESCAPE_USER_PREFIX_LEN) == 0; else return strncmp(name, OVL_XATTR_ESCAPE_TRUSTED_PREFIX, - OVL_XATTR_ESCAPE_TRUSTED_PREFIX_LEN - 1) == 0; + OVL_XATTR_ESCAPE_TRUSTED_PREFIX_LEN) == 0; } static bool ovl_is_own_xattr(struct super_block *sb, const char *name)