[PATCH] memory error #11836

[Noel Power]

Please find a patch for review, I opened bug
https://bugzilla.samba.org/show_bug.cgi?id=11836 for it (for backports)

it solves the following valgrind report

==31432== Invalid read of size 8
==31432==    at 0x99B8858: smbc_free_context (libsmb_context.c:260)
==31432==    by 0x5E6401: torture_libsmbclient_opendir (libsmbclient.c:136)
==31432==    by 0x9553F42: wrap_simple_test (torture.c:632)
==31432==    by 0x955366F: internal_torture_run_test (torture.c:442)
==31432==    by 0x95538C3: torture_run_tcase_restricted (torture.c:506)
==31432==    by 0x9553278: torture_run_suite_restricted (torture.c:357)
==31432==    by 0x95531D7: torture_run_suite (torture.c:339)
==31432==    by 0x25FEFF: run_matching (smbtorture.c:93)
==31432==    by 0x260195: torture_run_named_tests (smbtorture.c:143)
==31432==    by 0x261E14: main (smbtorture.c:665)
==31432==  Address 0x18864a70 is 80 bytes inside a block of size 96 free'd
==31432==    at 0x4C2A37C: free (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==31432==    by 0x99BCC46: SMBC_closedir_ctx (libsmb_dir.c:922)
==31432==    by 0x99C06CA: SMBC_close_ctx (libsmb_file.c:370)
==31432==    by 0x99B8853: smbc_free_context (libsmb_context.c:259)
==31432==    by 0x5E6401: torture_libsmbclient_opendir (libsmbclient.c:136)
==31432==    by 0x9553F42: wrap_simple_test (torture.c:632)
==31432==    by 0x955366F: internal_torture_run_test (torture.c:442)
==31432==    by 0x95538C3: torture_run_tcase_restricted (torture.c:506)
==31432==    by 0x9553278: torture_run_suite_restricted (torture.c:357)
==31432==    by 0x95531D7: torture_run_suite (torture.c:339)
==31432==    by 0x25FEFF: run_matching (smbtorture.c:93)
==31432==    by 0x260195: torture_run_named_tests (smbtorture.c:143)


-------------- next part --------------
From a2dcff6af515a7920921d58dad476c32de639560 Mon Sep 17 00:00:00 2001
From: Noel Power <noel.power at suse.com>
Date: Wed, 13 Apr 2016 17:57:31 +0100
Subject: [PATCH] Fix illegal memory access after memory has been deleted.

smbtorture with the libsmbclient test suite produces the following valgrind
trace

==31432== Invalid read of size 8
==31432==    at 0x99B8858: smbc_free_context (libsmb_context.c:260)
==31432==    by 0x5E6401: torture_libsmbclient_opendir (libsmbclient.c:136)
==31432==    by 0x9553F42: wrap_simple_test (torture.c:632)
==31432==    by 0x955366F: internal_torture_run_test (torture.c:442)
==31432==    by 0x95538C3: torture_run_tcase_restricted (torture.c:506)
==31432==    by 0x9553278: torture_run_suite_restricted (torture.c:357)
==31432==    by 0x95531D7: torture_run_suite (torture.c:339)
==31432==    by 0x25FEFF: run_matching (smbtorture.c:93)
==31432==    by 0x260195: torture_run_named_tests (smbtorture.c:143)
==31432==    by 0x261E14: main (smbtorture.c:665)
==31432==  Address 0x18864a70 is 80 bytes inside a block of size 96 free'd
==31432==    at 0x4C2A37C: free (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==31432==    by 0x99BCC46: SMBC_closedir_ctx (libsmb_dir.c:922)
==31432==    by 0x99C06CA: SMBC_close_ctx (libsmb_file.c:370)
==31432==    by 0x99B8853: smbc_free_context (libsmb_context.c:259)
==31432==    by 0x5E6401: torture_libsmbclient_opendir (libsmbclient.c:136)
==31432==    by 0x9553F42: wrap_simple_test (torture.c:632)
==31432==    by 0x955366F: internal_torture_run_test (torture.c:442)
==31432==    by 0x95538C3: torture_run_tcase_restricted (torture.c:506)
==31432==    by 0x9553278: torture_run_suite_restricted (torture.c:357)
==31432==    by 0x95531D7: torture_run_suite (torture.c:339)
==31432==    by 0x25FEFF: run_matching (smbtorture.c:93)
==31432==    by 0x260195: torture_run_named_tests (smbtorture.c:143)
Signed-off-by: Noel Power <noel.power at suse.com>
---
 source3/libsmb/libsmb_context.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/source3/libsmb/libsmb_context.c b/source3/libsmb/libsmb_context.c
index 5e31dfb..a956058 100644
--- a/source3/libsmb/libsmb_context.c
+++ b/source3/libsmb/libsmb_context.c
@@ -256,8 +256,9 @@ smbc_free_context(SMBCCTX *context,
 
                 f = context->internal->files;
                 while (f) {
+			SMBCFILE *next = f->next;
                         smbc_getFunctionClose(context)(context, f);
-                        f = f->next;
+			f = next;
                 }
                 context->internal->files = NULL;
 
-- 
2.1.4