reset: clear_unpack_trees_porcelain to plug leak

setup_unpack_trees_porcelain() populates various fields on
unpack_tree_opts, we need to call clear_unpack_trees_porcelain() to
avoid leaking them. Specifically, we used to leak
unpack_tree_opts.msgs_to_free.

We have to do this in leave_reset_head because there are multiple
scenarios where unpack_tree_opts has already been configured, followed
by a 'goto leave_reset_head'. But we can also 'goto leave_reset_head'
prior to having initialised unpack_tree_opts via memset(..., 0, ...).
Therefore we also move unpack_tree_opts initialisation to the start of
reset_head(), and convert it to use brace initialisation - which
guarantees that we can never clear an uninitialised unpack_tree_opts.
clear_unpack_tree_opts() is always safe to call as long as
unpack_tree_opts is at least zero-initialised, i.e. it does not depend
on a previous call to setup_unpack_trees_porcelain().

LSAN output from t0021:

Direct leak of 192 byte(s) in 1 object(s) allocated from:
    #0 0x49ab49 in realloc ../projects/compiler-rt/lib/asan/asan_malloc_linux.cpp:164:3
    #1 0xa721e5 in xrealloc wrapper.c:126:8
    #2 0x9f7861 in strvec_push_nodup strvec.c:19:2
    #3 0x9f7861 in strvec_pushf strvec.c:39:2
    #4 0xa43e14 in setup_unpack_trees_porcelain unpack-trees.c:129:3
    #5 0x97e011 in reset_head reset.c:53:2
    #6 0x61dfa5 in cmd_rebase builtin/rebase.c:1991:9
    #7 0x4ce83e in run_builtin git.c:475:11
    #8 0x4ccafe in handle_builtin git.c:729:3
    #9 0x4cb01c in run_argv git.c:818:4
    #10 0x4cb01c in cmd_main git.c:949:19
    #11 0x6b3f3d in main common-main.c:52:11
    #12 0x7fa8addf3349 in __libc_start_main (/lib64/libc.so.6+0x24349)

Indirect leak of 147 byte(s) in 1 object(s) allocated from:
    #0 0x49ab49 in realloc ../projects/compiler-rt/lib/asan/asan_malloc_linux.cpp:164:3
    #1 0xa721e5 in xrealloc wrapper.c:126:8
    #2 0x9e8d54 in strbuf_grow strbuf.c:98:2
    #3 0x9e8d54 in strbuf_vaddf strbuf.c:401:3
    #4 0x9f7774 in strvec_pushf strvec.c:36:2
    #5 0xa43e14 in setup_unpack_trees_porcelain unpack-trees.c:129:3
    #6 0x97e011 in reset_head reset.c:53:2
    #7 0x61dfa5 in cmd_rebase builtin/rebase.c:1991:9
    #8 0x4ce83e in run_builtin git.c:475:11
    #9 0x4ccafe in handle_builtin git.c:729:3
    #10 0x4cb01c in run_argv git.c:818:4
    #11 0x4cb01c in cmd_main git.c:949:19
    #12 0x6b3f3d in main common-main.c:52:11
    #13 0x7fa8addf3349 in __libc_start_main (/lib64/libc.so.6+0x24349)

Indirect leak of 134 byte(s) in 1 object(s) allocated from:
    #0 0x49ab49 in realloc ../projects/compiler-rt/lib/asan/asan_malloc_linux.cpp:164:3
    #1 0xa721e5 in xrealloc wrapper.c:126:8
    #2 0x9e8d54 in strbuf_grow strbuf.c:98:2
    #3 0x9e8d54 in strbuf_vaddf strbuf.c:401:3
    #4 0x9f7774 in strvec_pushf strvec.c:36:2
    #5 0xa43fe4 in setup_unpack_trees_porcelain unpack-trees.c:168:3
    #6 0x97e011 in reset_head reset.c:53:2
    #7 0x61dfa5 in cmd_rebase builtin/rebase.c:1991:9
    #8 0x4ce83e in run_builtin git.c:475:11
    #9 0x4ccafe in handle_builtin git.c:729:3
    #10 0x4cb01c in run_argv git.c:818:4
    #11 0x4cb01c in cmd_main git.c:949:19
    #12 0x6b3f3d in main common-main.c:52:11
    #13 0x7fa8addf3349 in __libc_start_main (/lib64/libc.so.6+0x24349)

Indirect leak of 130 byte(s) in 1 object(s) allocated from:
    #0 0x49ab49 in realloc ../projects/compiler-rt/lib/asan/asan_malloc_linux.cpp:164:3
    #1 0xa721e5 in xrealloc wrapper.c:126:8
    #2 0x9e8d54 in strbuf_grow strbuf.c:98:2
    #3 0x9e8d54 in strbuf_vaddf strbuf.c:401:3
    #4 0x9f7774 in strvec_pushf strvec.c:36:2
    #5 0xa43f20 in setup_unpack_trees_porcelain unpack-trees.c:150:3
    #6 0x97e011 in reset_head reset.c:53:2
    #7 0x61dfa5 in cmd_rebase builtin/rebase.c:1991:9
    #8 0x4ce83e in run_builtin git.c:475:11
    #9 0x4ccafe in handle_builtin git.c:729:3
    #10 0x4cb01c in run_argv git.c:818:4
    #11 0x4cb01c in cmd_main git.c:949:19
    #12 0x6b3f3d in main common-main.c:52:11
    #13 0x7fa8addf3349 in __libc_start_main (/lib64/libc.so.6+0x24349)

SUMMARY: AddressSanitizer: 603 byte(s) leaked in 4 allocation(s).

Signed-off-by: Andrzej Hunt <andrzej@ahunt.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/reset.c b/reset.c
index 4bea758053bbea3cb68aba7662d3ad92ac81ca43..79310ae071b7e897e71d6778926b6e7d21869647 100644 (file)
--- a/reset.c
+++ b/reset.c
@@ -21,7 +21,7 @@ int reset_head(struct repository *r, struct object_id *oid, const char *action,
        struct object_id head_oid;
        struct tree_desc desc[2] = { { NULL }, { NULL } };
        struct lock_file lock = LOCK_INIT;
-       struct unpack_trees_options unpack_tree_opts;
+       struct unpack_trees_options unpack_tree_opts = { 0 };
        struct tree *tree;
        const char *reflog_action;
        struct strbuf msg = STRBUF_INIT;
@@ -49,7 +49,6 @@ int reset_head(struct repository *r, struct object_id *oid, const char *action,
        if (refs_only)
                goto reset_head_refs;
 
-       memset(&unpack_tree_opts, 0, sizeof(unpack_tree_opts));
        setup_unpack_trees_porcelain(&unpack_tree_opts, action);
        unpack_tree_opts.head_idx = 1;
        unpack_tree_opts.src_index = r->index;
@@ -134,6 +133,7 @@ reset_head_refs:
 leave_reset_head:
        strbuf_release(&msg);
        rollback_lock_file(&lock);
+       clear_unpack_trees_porcelain(&unpack_tree_opts);
        while (nr)
                free((void *)desc[--nr].buffer);
        return ret;