If the user sets xattr->name[0] to NUL then we would read one character
before the start of the array. This bug seems harmless as far as I can
see but perhaps it would trigger a warning in KASAN.
Fixes: fa516b66a1bf ("EVM: Allow runtime modification of the set of verified xattrs")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
---
The user can pass a zeroed buffer to memdup_user_nul() so we can't rely
on "count" to test this.
diff --git a/security/integrity/evm/evm_secfs.c b/security/integrity/evm/evm_secfs.c
index a7a0a1acae99..94c739180a0b 100644
--- a/security/integrity/evm/evm_secfs.c
+++ b/security/integrity/evm/evm_secfs.c
@@ -207,7 +207,7 @@ static ssize_t evm_write_xattrs(struct file *file, const char __user *buf,
/* Remove any trailing newline */
len = strlen(xattr->name);
- if (xattr->name[len-1] == '\n')
+ if (len && xattr->name[len-1] == '\n')
xattr->name[len-1] = '\0';
if (strcmp(xattr->name, ".") == 0) {
--
To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
