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ovl: fix trusted xattr escape prefix matching

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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: dad02fad84 ("ovl: Support escaped overlay.* xattrs")
Signed-off-by: Yichong Chen <chenyichong@uniontech.com>
Link: https://patch.msgid.link/20260708082221.633602-1-chenyichong@uniontech.com
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
This commit is contained in:
Yichong Chen 2026-07-08 16:22:21 +08:00 committed by Christian Brauner
parent f80aa78576
commit a8e72879cd
1 changed files with 1 additions and 1 deletions
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2
fs/overlayfs/xattrs.c
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@ -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)