EVM: prevent array underflow in evm_write_xattrs()

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: fa516b6 ("EVM: Allow runtime modification of the set of verified xattrs") Signed-off-by: Dan Carpenter <[email protected]> Signed-off-by: Mimi Zohar <[email protected]>
XGWang0 · May 31, 2018 · a41d80a · a41d80a
1 parent 72acd64
commit a41d80a
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/security/integrity/evm/evm_secfs.c b/security/integrity/evm/evm_secfs.c
@@ -209,7 +209,7 @@ 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) {