Re: [Bug-tar] [PATCH] --one-top-level: avoid a heap-buffer-overflow

[Sergey Poznyakoff]

Jim Meyering <address@hidden> ha escrit:

>   $ : > k && tar cf k.tar k; valgrind tar --one-top-level -tf k.tar
>
>   Invalid read of size 1
>      at 0x421FCF: strip_compression_suffix (suffix.c:107)

Thanks for finding that out. However, the proposed fix doesn't seem
quite correct to me:

> +      size_t len = (strncmp (name + base_len, ".tar", 4) == 0
> +                 ? base_len : strlen (name));

This will result in returning entire string, except if it ends in
".tar" followed by compression suffix. The idea was, however, to
strip off the compression suffix *and* eventual ".tar" before it.

I would suggest the following simple fix:

diff --git a/src/suffix.c b/src/suffix.c
index 66b5694..6cb521a 100644
--- a/src/suffix.c
+++ b/src/suffix.c
@@ -104,7 +104,7 @@ strip_compression_suffix (const char *name)
 
   if (find_compression_suffix (name, &len))
     {
-      if (strncmp (name + len - 4, ".tar", 4) == 0)
+      if (len > 4 && memcmp (name + len - 4, ".tar", 4) == 0)
        len -= 4;
       if (len == 0)
        return NULL;

Regards,
Sergey