From: Han Pingtian <hanpt@linux.vnet.ibm.com>
To: zsh-workers@zsh.org
Subject: Re: zsh 5.0.5-dev-2
Date: Fri, 15 Aug 2014 19:23:16 +0800 [thread overview]
Message-ID: <20140815112316.GA17063@localhost.localdomain> (raw)
In-Reply-To: <140814214412.ZM4177@torch.brasslantern.com>
Hi,
Looks like on the 747 line of Src/utils.c:
747 sprintf(xbuf2, "%s/%s", xbuf, *pp);
The "cd .." will trigger a buffer overflow if I compile zsh with
-D FORTIFY_SOURCE=2 . Shall we return -1 here if it will overflow xbuf2?
On Thu, Aug 14, 2014 at 09:44:12PM -0700, Bart Schaefer wrote:
> On Aug 14, 8:54pm, Peter Stephenson wrote:
> }
> } It's entirely unclear to me from looking at xsymlinks() when an empty
> } xbuf would actually constitute a failure.
>
> This occurs in the (t0 == -1) case when the reason that readlink() has
> failed is because the path so far concatenated with the next segment of
> the split path has produced a string longer than PATH_MAX. In that case
> (xbuflen + pplen > sizeof(xbuf)) we completely truncate xbuf and give up.
>
> } If it can't expand something
> } as a symbolic link it simply treats it literally;
>
> Yes, but for a /path/to/somereallylongname, appending somereallylongname
> to the expansion of xbuf so far, might overflow xbuf.
>
> } If we don't have an answer now I'd be inclined to comment out the
> } warning.
>
> Maybe just make xsymlinks() have a ternary return value instead of a
> boolean one, and return an actual error value in the case where we've
> truncated on overflow instead of as part of normal expansion to root?
>
> I don't know if all of these changes are necessary. It has always
> bothered me that the return value of the recursive calls to xsymlinks()
> are ignored, but maybe this isn't the right way to handle them.
>
> Incidentally, anybody recall what the obviously obsolete comment above
> the xsymlinks() definition in Src/utils.c is about?
>
> diff --git a/Src/utils.c b/Src/utils.c
> index 998e46a..076a33c 100644
> --- a/Src/utils.c
> +++ b/Src/utils.c
> @@ -716,7 +716,6 @@ slashsplit(char *s)
> }
>
> /* expands symlinks and .. or . expressions */
> -/* if flag = 0, only expand .. and . expressions */
>
> /**/
> static int
> @@ -753,6 +752,7 @@ xsymlinks(char *s)
> strcat(xbuf, *pp);
> } else {
> *xbuf = 0;
> + ret = -1;
> break;
> }
> } else {
> @@ -760,9 +760,11 @@ xsymlinks(char *s)
> metafy(xbuf3, t0, META_NOALLOC);
> if (*xbuf3 == '/') {
> strcpy(xbuf, "");
> - xsymlinks(xbuf3 + 1);
> + if (xsymlinks(xbuf3 + 1) < 0)
> + ret = -1;
> } else
> - xsymlinks(xbuf3);
> + if (xsymlinks(xbuf3) < 0)
> + ret = -1;
> }
> }
> freearray(opp);
> @@ -781,11 +783,10 @@ xsymlink(char *s)
> if (*s != '/')
> return NULL;
> *xbuf = '\0';
> - xsymlinks(s + 1);
> - if (!*xbuf) {
> + if (xsymlinks(s + 1) < 0)
> zwarn("path expansion failed, using root directory");
> + if (!*xbuf)
> return ztrdup("/");
> - }
> return ztrdup(xbuf);
> }
>
> @@ -795,7 +796,7 @@ print_if_link(char *s)
> {
> if (*s == '/') {
> *xbuf = '\0';
> - if (xsymlinks(s + 1))
> + if (xsymlinks(s + 1) > 0)
> printf(" -> "), zputs(*xbuf ? xbuf : "/", stdout);
> }
> }
>
> --
> Barton E. Schaefer
next prev parent reply other threads:[~2014-08-15 11:33 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-12 20:29 Peter Stephenson
2014-08-12 22:36 ` Axel Beckert
2014-08-13 14:04 ` zsh 5.0.5-dev-2 / Occassional hangs on Test/A05execution.ztst Axel Beckert
2014-08-13 19:08 ` Bart Schaefer
2014-08-14 8:48 ` Axel Beckert
2014-08-14 8:50 ` Peter Stephenson
2014-08-14 16:25 ` Bart Schaefer
2014-08-14 16:31 ` Axel Beckert
2014-08-14 17:34 ` Axel Beckert
2014-08-15 4:50 ` Bart Schaefer
2014-08-15 9:32 ` Axel Beckert
2014-08-15 17:33 ` Bart Schaefer
2014-08-15 19:42 ` Axel Beckert
2014-08-16 18:12 ` zsh 5.0.5/6 Peter Stephenson
2014-08-13 17:28 ` zsh 5.0.5-dev-2 Dominic Hopf
2014-08-13 22:34 ` Oliver Kiddle
2014-08-14 8:34 ` Peter Stephenson
2014-08-14 9:32 ` Peter Stephenson
2014-08-14 16:20 ` Bart Schaefer
2014-08-14 19:54 ` Peter Stephenson
2014-08-15 4:44 ` Bart Schaefer
2014-08-15 8:38 ` Peter Stephenson
2014-08-15 11:23 ` Han Pingtian [this message]
2014-08-15 17:17 ` Bart Schaefer
2014-08-16 0:35 ` Han Pingtian
2014-08-17 17:30 ` Bart Schaefer
2014-08-18 2:56 ` Han Pingtian
2014-08-18 6:36 ` Bart Schaefer
2014-08-18 14:02 ` Han Pingtian
2014-08-23 17:51 ` Symlink chasing Peter Stephenson
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