From: Shaoxuan Yuan <shaoxuan.yuan02@gmail.com>
To: shaoxuan.yuan02@gmail.com
Cc: derrickstolee@github.com, git@vger.kernel.org, gitster@pobox.com,
peff@peff.net, vdye@github.com
Subject: [PATCH v2] builtin/mv.c: fix possible segfault in add_slash()
Date: Fri, 9 Sep 2022 12:44:58 -0700 [thread overview]
Message-ID: <20220909194458.264735-1-shaoxuan.yuan02@gmail.com> (raw)
In-Reply-To: <20220908230223.239970-1-shaoxuan.yuan02@gmail.com>
A possible segfault was introduced in c08830de41 (mv: check if
<destination> is a SKIP_WORKTREE_DIR, 2022-08-09).
When running t7001 with SANITIZE=address, problem appears when running:
git mv path1/path2/ .
or
git mv directory ../
or
any <destination> that makes dest_path[0] an empty string.
The add_slash() call could segfault when dest_path[0] is an empty string,
because it was accessing a null value in such case.
Change add_slash() to check the path argument is a non-empty string
before accessing its value. If the path is empty, return it as-is.
Explanation:
It's OK for add_slash() to return an empty string as-is. add_slash()
converts its path argument to the prefix (for "folder1/file1",
"folder1/" is the prefix we mean here) for the result path. The path
argument is an empty string _iff_ the result path is analyzed to be at
the top level (this normalization process is done earlier by
internal_prefix_pathspec()).
Because the prefix for a top-level path is an empty string, thus
add_slash() should return an empty path argument as-is, both for
correctness and avoiding inappropriate memory access.
Reported-by: Jeff King <peff@peff.net>
Helped-by: Jeff King <peff@peff.net>
Helped-by: Junio C Hamano <gitster@pobox.com>
Helped-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Shaoxuan Yuan <shaoxuan.yuan02@gmail.com>
---
Range-diff against v1:
1: a5dccc030c ! 1: 82353f457d builtin/mv.c: fix possible segfault in add_slash()
@@ Commit message
or
any <destination> that makes dest_path[0] an empty string.
- The add_slash() call segfaults when dest_path[0] is an empty string,
+ The add_slash() call could segfault when dest_path[0] is an empty string,
because it was accessing a null value in such case.
Change add_slash() to check the path argument is a non-empty string
- before accessing its value.
+ before accessing its value. If the path is empty, return it as-is.
- The purpose of add_slash() is adding a slash to the end of a string to
- construct a directory path. And, because adding a slash to an empty
- string is of no use here, and checking the string value without checking
- it is non-empty leads to segfault, we should make sure the length of the
- string is positive to solve both problems.
+ Explanation:
+
+ It's OK for add_slash() to return an empty string as-is. add_slash()
+ converts its path argument to the prefix (for "folder1/file1",
+ "folder1/" is the prefix we mean here) for the result path. The path
+ argument is an empty string _iff_ the result path is analyzed to be at
+ the top level (this normalization process is done earlier by
+ internal_prefix_pathspec()).
+
+ Because the prefix for a top-level path is an empty string, thus
+ add_slash() should return an empty path argument as-is, both for
+ correctness and avoiding inappropriate memory access.
Reported-by: Jeff King <peff@peff.net>
Helped-by: Jeff King <peff@peff.net>
+ Helped-by: Junio C Hamano <gitster@pobox.com>
+ Helped-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Shaoxuan Yuan <shaoxuan.yuan02@gmail.com>
## builtin/mv.c ##
builtin/mv.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/builtin/mv.c b/builtin/mv.c
index 2d64c1e80f..3413ad1c9b 100644
--- a/builtin/mv.c
+++ b/builtin/mv.c
@@ -71,7 +71,7 @@ static const char **internal_prefix_pathspec(const char *prefix,
static const char *add_slash(const char *path)
{
size_t len = strlen(path);
- if (path[len - 1] != '/') {
+ if (len && path[len - 1] != '/') {
char *with_slash = xmalloc(st_add(len, 2));
memcpy(with_slash, path, len);
with_slash[len++] = '/';
base-commit: e71f9b1de6941c8b449d0c0e17e457f999664bc9
--
2.37.0
next prev parent reply other threads:[~2022-09-09 19:48 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-08 23:02 [PATCH] builtin/mv.c: fix possible segfault in add_slash() Shaoxuan Yuan
2022-09-09 2:21 ` Jeff King
2022-09-09 14:14 ` Derrick Stolee
2022-09-09 16:37 ` Junio C Hamano
2022-09-09 19:44 ` Shaoxuan Yuan [this message]
2022-09-09 20:04 ` [PATCH v2] " Junio C Hamano
2022-09-09 22:40 ` Shaoxuan Yuan
2022-09-09 22:27 ` [PATCH v3] " Shaoxuan Yuan
2022-09-09 22:52 ` Junio C Hamano
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