threads / patch / 36052

patchSetup.c: PATH_MAX is the length including the Nil

Subject: [PATCH] Setup.c: PATH_MAX is the length including the Nil

## tl;dr

2 messages between Mar 4, 2014 and Mar 4, 2014. Diffs are folded; open one to read it.

replies: 1people: 2as markdown or json

Sun He· Mar 4, 2014, 16:29 UTC · lore

Signed-off-by: Sun He <sunheehnus@gmail.com>
---

Check the limit.h of linux and find out that the MACRO #define PATH_MAX 4096 /* # chars in a path name including nul */ So if the magic number 40 is just the size it should be. (e.g. hash code) It may bring bugs with the length(4056) of long name(gitdirenv). As gitdirenv could be set by GIT_DIR_ENVIRONMENT. If it is a bug, it will almost never occur. But I need your help to know if there is the PATH_MAX of git is the mirror of the PATH_MAX of linux and if this fix is right? If it was, there may be many places like "PATH_MAX + 1" could be replaced by just "PATH_MAX". And there may be many places like this.

Cheers, He Sun

 setup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Show changes to setup.c +1 −1

diff --git a/setup.c b/setup.c
index cffb6d6..1511612 100644
--- a/setup.c
+++ b/setup.c
@@ -395,7 +395,7 @@ static const char *setup_explicit_git_dir(const char *gitdirenv,
 	char *gitfile;
 	int offset;
 
-	if (PATH_MAX - 40 < strlen(gitdirenv))
+	if (PATH_MAX - 41 < strlen(gitdirenv))
 		die("'$%s' too big", GIT_DIR_ENVIRONMENT);
 
 	gitfile = (char*)read_gitfile(gitdirenv);

-- 
1.9.0.138.g2de3478.dirty

Faiz Kothari· Mar 4, 2014, 16:49 UTC · re: Sun He · lore

Re: [PATCH] Setup.c: PATH_MAX is the length including the Nil

On Tue, Mar 4, 2014 at 9:59 PM, Sun He <sunheehnus@gmail.com> wrote:

Show 16 quoted lines

> Signed-off-by: Sun He <sunheehnus@gmail.com>
> ---
>
> Check the limit.h of linux and find out that the MACRO
> #define PATH_MAX        4096    /* # chars in a path name including nul */
> So if the magic number 40 is just the size it should be. (e.g. hash code)
> It may bring bugs with the length(4056) of long name(gitdirenv).
> As gitdirenv could be set by GIT_DIR_ENVIRONMENT.
> If it is a bug, it will almost never occur.
> But I need your help to know if there is the PATH_MAX of git is the mirror of the
> PATH_MAX of linux and if this fix is right?
> If it was, there may be many places like "PATH_MAX + 1" could be replaced by
> just "PATH_MAX". And there may be many places like this.
>
> Cheers,
> He Sun

Hi, I am not getting what exactly you are trying to tell, but git defines its own PATH_MAX. Its defined in git-compat-util.h: #define PATH_MAX 4096 That is why instead of making buffers using PATH_MAX, use strbuf. All these problems of buffer overflow will be gone. I hope you are concerned about buffer overflow.

Cheers

-Faiz