[PATCH 2/3] prune_object_dir(): verify that path fits in the temporary buffer

[Michael Haggerty <mhagger@alum.mit.edu>]

Dimension the buffer based on PATH_MAX rather than a magic number, and
verify that the path fits in it before continuing.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
---

I don't think that this problem is remotely exploitable, because the
size of the string doesn't depend on inputs that can be influenced by
a client (at least not within Git).

 builtin/prune.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/builtin/prune.c b/builtin/prune.c
index 6366917..ae34d04 100644
--- a/builtin/prune.c
+++ b/builtin/prune.c
@@ -96,7 +96,9 @@ static void prune_object_dir(const char *path)
 {
 	int i;
 	for (i = 0; i < 256; i++) {
-		static char dir[4096];
+		static char dir[PATH_MAX + 1];
+		if (strlen(path) + 3 > PATH_MAX)
+			die("impossible object directory");
 		sprintf(dir, "%s/%02x", path, i);
 		prune_dir(i, dir);
 	}
-- 
1.8.5.1