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dfilter: fix memleak when using value_string values 

When using a filter such as "ncp.alloc_reply_lvl2 == FALSE", a memory
leak would occur as follows:

 1. dfilter_fvalue_from_unparsed is called and
 2. ends up calling _uint64_from_unparsed
 3. which fails with error message "\"FALSE\" is not a valid number.".
 4. Next, mk_fvalue_from_val_string is called which maps "FALSE" to 0
 5. and the filter is successfully compiled.
 6. dfwork_free deliberately does not free the error message (since
    there should be none at this point) and we have a memleak (from 3).

Fix this memleak by clearing the error message when a successful
value_string mapping is found.

Change-Id: I78d59a4336342b09dc5448ea994b2e1d199d7f3f
Link: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=1302
Reviewed-on: https://code.wireshark.org/review/21497
Petri-Dish: Peter Wu <peter@lekensteyn.nl>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Alexis La Goutte <alexis.lagoutte@gmail.com>
This commit is contained in:
Peter Wu 2017-05-04 17:57:23 +02:00 committed by Alexis La Goutte
parent 98d87038a7
commit 2f35a811a3
1 changed files with 9 additions and 0 deletions
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9
epan/dfilter/semcheck.c
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@ -717,6 +717,15 @@ check_relation_LHS_FIELD(dfwork_t *dfw, const char *relation_string,
if (!fvalue && type2 != STTYPE_CHARCONST) {
/* check value_string */
fvalue = mk_fvalue_from_val_string(dfw, hfinfo1, s);
/*
* Ignore previous errors if this can be mapped
* to an item from value_string.
*/
if (fvalue && dfw->error_message) {
g_free(dfw->error_message);
dfw->error_message = NULL;
}
}
}