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Re: [PATCH] Fix _nl_find_msg malloc failure case, and callers.
- From: Andreas Jaeger <aj at suse dot com>
- To: GNU C Library <libc-alpha at sourceware dot org>
- Date: Thu, 09 May 2013 09:24:33 +0200
- Subject: Re: [PATCH] Fix _nl_find_msg malloc failure case, and callers.
- References: <51892FCE dot 5030506 at redhat dot com>
On 05/07/2013 06:46 PM, Carlos O'Donell wrote:
Community,
This patch fixes two issues, and perhaps should be two distinct patches,
but I present it here as one for the sake of completeness.
This commit:
commit 006dd86111c44572dbd3b26e9c63dd0f834d7762
Author: Jeff Law <law at redhat.com>
Date: Thu Jun 21 17:15:38 2012 -0600
[BZ #14277]
* intl/dcigettext.c (_nl_find_msg): Avoid use after potential
free. Simplify list management for _LIBC case.
Fails to check malloc's return in intl/dcigettext.c (_nl_find_msg):
~~~~
freemem_size = INITIAL_BLOCK_SIZE;
newmem = (transmem_block_t *) malloc (freemem_size);
# ifdef _LIBC
/* Add the block to the list of blocks we have to free
at some point. */
newmem->next = transmem_list;
transmem_list = newmem;
~~~
If malloc fails then newmem is NULL then newmem->next results in a fault.
The fix is easy enough, check for newmem != NULL, and fall through to
the error condition below which returns (char *) -1 e.g. resource error.
The problem is that returning (char *) -1 will break all sorts of other
code, so while what we did is correct, the real failure case fix is slightly
broader.
There are 4 other places where _nl_find_msg is called:
(a) Recursively in _nl_find_msg.
Here we return -1 immediately if a recursive call to _nl_find_msg
returns -1. Resource errors are fatal at this point and if we
continue it just makes the matter worse by trying to allocate other
structure like conv_tab.
(b) From _nl_load_domain.
Here the error is also fatal, the domain is incomplete without
pluralization information and the failure in _nl_find_msg means
we won't be able to setup pluralization. We finalize the lock
we just initialized and exit via the normal error path.
(c) Twice from DCIGETTEXT.
In both cases the error is not fatal, it just means we have no
translation and return the original message. We patch the second
call to _nl_find_msg to ensure that future maintenance on the
function doesn't move the check for -1 further away.
No regressions on x86-64 or x86.
However, no regressions isn't really a useful metric for this code.
The change was tested as documented here:
http://sourceware.org/glibc/wiki/Testing/WhiteBox
OK to checkin?
This looks fine, thanks,
Andreas
--
Andreas Jaeger aj@{suse.com,opensuse.org} Twitter/Identica: jaegerandi
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