From: Junio C Hamano <gitster@pobox.com>
To: "Johannes Schindelin via GitGitGadget" <gitgitgadget@gmail.com>
Cc: git@vger.kernel.org, Johannes Schindelin <johannes.schindelin@gmx.de>
Subject: Re: [PATCH 06/11] pack-redundant: avoid using uninitialized memory
Date: Wed, 15 Jun 2022 21:53:01 -0700 [thread overview]
Message-ID: <xmqqilp1w6oi.fsf@gitster.g> (raw)
In-Reply-To: <bc29a9710e3a22e6d660098c4f201f3bfecc54ea.1655336146.git.gitgitgadget@gmail.com> (Johannes Schindelin via GitGitGadget's message of "Wed, 15 Jun 2022 23:35:40 +0000")
"Johannes Schindelin via GitGitGadget" <gitgitgadget@gmail.com>
writes:
> From: Johannes Schindelin <johannes.schindelin@gmx.de>
>
> In the `add_pack()` function, we forgot to initialize the field `next`,
> which could potentially lead to readin uninitialized memory later.
>
> Reported by Coverity.
>
> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> ---
> builtin/pack-redundant.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/builtin/pack-redundant.c b/builtin/pack-redundant.c
> index ed9b9013a5f..1f7da1f68b6 100644
> --- a/builtin/pack-redundant.c
> +++ b/builtin/pack-redundant.c
> @@ -526,6 +526,7 @@ static struct pack_list * add_pack(struct packed_git *p)
> }
> l.all_objects_size = l.remaining_objects->size;
> l.unique_objects = NULL;
> + l.next = NULL;
> if (p->pack_local)
> return pack_list_insert(&local_packs, &l);
> else
return pack_list_insert(&altodb_packs, &l);
The pack_list_insert reads like so:
static inline struct pack_list * pack_list_insert(struct pack_list **pl,
struct pack_list *entry)
{
struct pack_list *p = xmalloc(sizeof(struct pack_list));
memcpy(p, entry, sizeof(struct pack_list));
p->next = *pl;
*pl = p;
return p;
}
IOW, we prepare members of "l", pass it as "entry" to pack_list_insert(),
but the helper function allocates a new piece of memory, copies "l"
to it, and then sets the .next member of it to a reasonable value.
And after that, the "l" that was merely used as a template goes out
of scope.
So I think this is a false positive. memcpy(p) does copy the
uninitialized garbage that is held in entry->next to p->next, but it
is overwritten with a reasonable address immediately after that.
next prev parent reply other threads:[~2022-06-16 4:53 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-15 23:35 [PATCH 00/11] Coverity fixes Johannes Schindelin via GitGitGadget
2022-06-15 23:35 ` [PATCH 01/11] mingw: avoid accessing uninitialized memory in `is_executable()` Johannes Schindelin via GitGitGadget
2022-06-16 4:07 ` Junio C Hamano
2022-06-16 19:53 ` René Scharfe
2022-06-16 20:13 ` Junio C Hamano
2022-06-16 20:20 ` Junio C Hamano
2022-06-15 23:35 ` [PATCH 02/11] fsmonitor: avoid memory leak in `fsm_settings__get_incompatible_msg()` Johannes Schindelin via GitGitGadget
2022-06-16 4:10 ` Junio C Hamano
2022-06-15 23:35 ` [PATCH 03/11] submodule--helper: avoid memory leak in `update_submodule()` Johannes Schindelin via GitGitGadget
2022-06-16 4:23 ` Junio C Hamano
2022-06-16 17:51 ` Glen Choo
2022-06-15 23:35 ` [PATCH 04/11] get_oid_with_context_1(): avoid use-after-free Johannes Schindelin via GitGitGadget
2022-06-16 4:29 ` Junio C Hamano
2022-06-15 23:35 ` [PATCH 05/11] submodule-config: avoid memory leak Johannes Schindelin via GitGitGadget
2022-06-16 4:36 ` Junio C Hamano
2022-06-16 18:09 ` Glen Choo
2022-06-15 23:35 ` [PATCH 06/11] pack-redundant: avoid using uninitialized memory Johannes Schindelin via GitGitGadget
2022-06-16 4:53 ` Junio C Hamano [this message]
2022-06-15 23:35 ` [PATCH 07/11] submodule--helper: avoid memory leak when fetching submodules Johannes Schindelin via GitGitGadget
2022-06-16 4:55 ` Junio C Hamano
2022-06-15 23:35 ` [PATCH 08/11] read_index_from(): avoid memory leak Johannes Schindelin via GitGitGadget
2022-06-17 21:27 ` Tom Levy
2022-06-15 23:35 ` [PATCH 09/11] pack-mtimes: avoid closing a bogus file descriptor Johannes Schindelin via GitGitGadget
2022-06-16 20:43 ` Taylor Blau
2022-06-15 23:35 ` [PATCH 10/11] relative_url(): fix incorrect condition Johannes Schindelin via GitGitGadget
2022-06-16 5:02 ` Junio C Hamano
2022-06-16 13:09 ` Ævar Arnfjörð Bjarmason
2022-06-16 17:55 ` Junio C Hamano
2022-06-16 16:41 ` Junio C Hamano
2022-06-15 23:35 ` [PATCH 11/11] bug_fl(): add missing `va_end()` call Johannes Schindelin via GitGitGadget
2022-06-16 4:53 ` Jeff King
2022-06-16 5:00 ` Junio C Hamano
2022-06-16 13:02 ` Ævar Arnfjörð Bjarmason
2022-06-16 18:03 ` Junio C Hamano
2022-06-16 19:20 ` Jeff King
2022-06-16 20:04 ` [PATCH] bug_fl(): correctly initialize trace2 va_list Jeff King
2022-06-16 20:11 ` [PATCH 11/11] bug_fl(): add missing `va_end()` call Junio C Hamano
2022-06-16 4:05 ` [PATCH 00/11] Coverity fixes Junio C Hamano
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