From: Jonathan Nieder <jrnieder@gmail.com>
To: Thomas Gummerer <t.gummerer@gmail.com>
Cc: git@vger.kernel.org, "Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>,
"Junio C Hamano" <gitster@pobox.com>
Subject: Re: [PATCH 1/3] path.c: fix uninitialized memory access
Date: Tue, 3 Oct 2017 15:45:01 -0700 [thread overview]
Message-ID: <20171003224501.GD19555@aiede.mtv.corp.google.com> (raw)
In-Reply-To: <20171003195713.13395-2-t.gummerer@gmail.com>
Hi,
Thomas Gummerer wrote:
> In cleanup_path we're passing in a char array, run a memcmp on it, and
> run through it without ever checking if something is in the array in the
> first place. This can lead us to access uninitialized memory, for
> example in t5541-http-push-smart.sh test 7, when run under valgrind:
[...]
> Avoid this by checking passing in the length of the string in the char
> array, and checking that we never run over it.
>
> Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
> ---
> path.c | 19 ++++++++++---------
> 1 file changed, 10 insertions(+), 9 deletions(-)
When I first read the above, I thought it was going to be about a
NUL-terminated string that was missing a NUL. But in fact, the issue
is that strlen(path) can be < 2.
In other words, an alternative fix would be
if (*path == '.' && path[1] == '/') {
...
}
which would not require passing in 'len' or switching to index-based
arithmetic. I think I prefer it. What do you think?
Thanks and hope that helps,
Jonathan
diff --git i/path.c w/path.c
index b533ec938d..3a1fbee1e0 100644
--- i/path.c
+++ w/path.c
@@ -37,7 +37,7 @@ static struct strbuf *get_pathname(void)
static char *cleanup_path(char *path)
{
/* Clean it up */
- if (!memcmp(path, "./", 2)) {
+ if (*path == '.' && path[1] == '/') {
path += 2;
while (*path == '/')
path++;
next prev parent reply other threads:[~2017-10-03 22:45 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-03 19:57 [PATCH 0/3] fixes for running the test suite with --valgrind Thomas Gummerer
2017-10-03 19:57 ` [PATCH 1/3] path.c: fix uninitialized memory access Thomas Gummerer
2017-10-03 22:45 ` Jonathan Nieder [this message]
2017-10-03 23:30 ` Jeff King
2017-10-03 23:37 ` Jonathan Nieder
2017-10-04 4:47 ` Junio C Hamano
2017-10-04 5:21 ` Jeff King
2017-10-04 19:22 ` Thomas Gummerer
2017-10-04 19:36 ` Jonathan Nieder
2017-10-03 19:57 ` [PATCH 2/3] http-push: fix construction of hex value from path Thomas Gummerer
2017-10-03 22:53 ` Jonathan Nieder
2017-10-03 23:36 ` Jeff King
2017-10-04 4:48 ` Junio C Hamano
2017-10-04 5:20 ` Junio C Hamano
2017-10-04 5:26 ` Jeff King
2017-10-04 6:26 ` Junio C Hamano
2017-10-03 19:57 ` [PATCH 3/3] sub-process: allocate argv on the heap Thomas Gummerer
2017-10-03 20:24 ` Johannes Sixt
2017-10-04 4:59 ` Junio C Hamano
2017-10-04 5:32 ` Jeff King
2017-10-04 5:58 ` Johannes Sixt
2017-10-04 19:31 ` Thomas Gummerer
2017-10-03 20:25 ` Stefan Beller
2017-10-03 23:41 ` [PATCH 0/3] fixes for running the test suite with --valgrind Jeff King
2017-10-03 23:50 ` Jonathan Nieder
2017-10-03 23:54 ` Jeff King
2017-10-04 10:19 ` playing with MSan, was " Jeff King
2017-10-04 19:30 ` Thomas Gummerer
2017-10-05 3:46 ` lstat-ing delayed-filter output, was Re: playing with MSan Jeff King
2017-10-05 10:47 ` Lars Schneider
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