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Re: [PATCH] getmntent: fix memory corruption w/blank lines [BZ #18887]
- From: OndÅej BÃlka <neleai at seznam dot cz>
- To: Mike Frysinger <vapier at gentoo dot org>
- Cc: libc-alpha at sourceware dot org
- Date: Sat, 29 Aug 2015 07:50:16 +0200
- Subject: Re: [PATCH] getmntent: fix memory corruption w/blank lines [BZ #18887]
- Authentication-results: sourceware.org; auth=none
- References: <1440796961-1773-1-git-send-email-vapier at gentoo dot org>
On Fri, Aug 28, 2015 at 05:22:41PM -0400, Mike Frysinger wrote:
> The fix for BZ #17273 added introduced a single byte of memory corruption
> when the line is entirely blank. It would walk back past the start of the
> buffer if the heap happened to be 0x20 or 0x09 and then write a NUL byte.
> buffer = '\n';
> end_ptr = buffer;
> while (end_ptr[-1] == ' ' || end_ptr[-1] == '\t')
> *end_ptr = '\0';
> Fix that and rework the tests. Adding the testcase for BZ #17273 does
> not really make sense as it's unrelated, and leads to confusing behavior:
> it implicitly relies on the new entry being written to the start of the
> file being longer than the previous entry since there is no truncation.
> Instead split it out into its own dedicated testcase.