[PATCH] erofs-utils: tar: guard slash-only header names

[Vansh Choudhary]

Check that the assembled header path is non-empty before trimming
trailing slashes from it.

A malformed tar header name made up only of '/' characters could
otherwise drive the trim loop to read before the start of the buffer.

Signed-off-by: Vansh Choudhary <ch at vnsh.in>
---
 lib/tar.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/tar.c b/lib/tar.c
index 4e97522..39e2321 100644
--- a/lib/tar.c
+++ b/lib/tar.c
@@ -866,7 +866,7 @@ out_eot:
 			path[1] = '\0';
 		} else {
 			*_path = '\0';
-			while (path[j - 1] == '/')
+			while (j && path[j - 1] == '/')
 				path[--j] = '\0';
 		}
 	}
-- 
2.43.0