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From 6fcb24d785a2c2d626bac6999aee6b3ab368be15 Mon Sep 17 00:00:00 2001
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From: Peter Jones <pjones@redhat.com>
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Date: Fri, 28 Jul 2017 16:11:40 -0400
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Subject: [PATCH] Don't leak the last argument expanded by expandNextArg()
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While using POPT_ARG_ARGV, I noticed this in valgrind's leak checker:
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==1738== HEAP SUMMARY:
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==1738== in use at exit: 8 bytes in 1 blocks
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==1738== total heap usage: 94 allocs, 93 frees, 42,319 bytes allocated
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==1738==
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==1738== 8 bytes in 1 blocks are definitely lost in loss record 1 of 1
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==1738== at 0x4C2EB6B: malloc (vg_replace_malloc.c:299)
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==1738== by 0x4E3DF47: expandNextArg (popt.c:699)
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==1738== by 0x4E3F681: poptGetNextOpt (popt.c:1501)
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==1738== by 0x401F72: main (bingrep.c:433)
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==1738==
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==1738== LEAK SUMMARY:
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==1738== definitely lost: 8 bytes in 1 blocks
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==1738== indirectly lost: 0 bytes in 0 blocks
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==1738== possibly lost: 0 bytes in 0 blocks
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==1738== still reachable: 0 bytes in 0 blocks
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==1738== suppressed: 0 bytes in 0 blocks
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My command line argument is a 7-byte string, and on first glance, it
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appears this is because both expandNextArg() and poptSaveString()
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duplicate the string. The copy from poptSaveString() is the consuming
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program's responsibility to free, but the intermediate pointer is popt's
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responsibility.
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Upon further examination, it appears popt normally does free this
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string, but it only does it on the next entry to poptGetNextOpt(), and
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on cleanOSE() in the case if we're not already at the bottom of
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con->OptionStack.
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This patch modifies poptResetContext() to ensure we'll always attempt to
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free con->os->nextArg regardless of our position in the OptionStack, and
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removes the duplicate free of con->os->argb in poptFreeContext(), as
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it's called unconditionally by the poptResetContext() call on the
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previous line.
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This ensures that if poptGetNextOpt() isn't re-intered, poptFreeContext()
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will free the memory that was allocated. Now valgrind tells me:
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==31734== HEAP SUMMARY:
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==31734== in use at exit: 0 bytes in 0 blocks
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==31734== total heap usage: 94 allocs, 94 frees, 42,319 bytes allocated
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==31734==
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==31734== All heap blocks were freed -- no leaks are possible
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Signed-off-by: Peter Jones <pjones@redhat.com>
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---
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popt.c | 3 +--
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1 file changed, 1 insertion(+), 2 deletions(-)
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diff --git a/popt.c b/popt.c
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index 1a53f40..72fbf5c 100644
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--- a/popt.c
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+++ b/popt.c
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@@ -230,7 +230,7 @@ void poptResetContext(poptContext con)
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con->os->argb = PBM_FREE(con->os->argb);
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con->os->currAlias = NULL;
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con->os->nextCharArg = NULL;
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- con->os->nextArg = NULL;
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+ con->os->nextArg = _free(con->os->nextArg);
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con->os->next = 1; /* skip argv[0] */
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con->numLeftovers = 0;
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@@ -1617,7 +1617,6 @@ poptContext poptFreeContext(poptContext con)
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{
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if (con == NULL) return con;
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poptResetContext(con);
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- con->os->argb = _free(con->os->argb);
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con->aliases = poptFreeItems(con->aliases, con->numAliases);
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con->numAliases = 0;
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--
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2.13.3
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