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Message-ID: <20170621232310.GI1627@brightrain.aerifal.cx>
Date: Wed, 21 Jun 2017 19:23:10 -0400
From: Rich Felker <dalias@...c.org>
To: musl@...ts.openwall.com
Subject: Re: [PATCH] fix getgrouplist without nscd
On Tue, Jul 12, 2016 at 11:30:57AM +0200, Joakim Sindholt wrote:
> There were two issues here. First, if socket() fails then it's
> treated as an unrecoverable error and second: the response buffer
> was not initialized and so a recoverable error (ie. no nscd) would
> result in UB.
>
> dgp tested this patch and confirmed on IRC that it worked in the
> no-nscd no-socket case and I have tested it in the has-nscd case.
> >From 9251aff794832e0e37f5b747b69e756ac836f181 Mon Sep 17 00:00:00 2001
> From: Joakim Sindholt <opensource@...sha.com>
> Date: Tue, 12 Jul 2016 10:13:23 +0200
> Subject: [PATCH] fix getgrouplist without nscd
>
> ---
> src/passwd/getgrouplist.c | 2 +-
> src/passwd/nscd_query.c | 8 +++++++-
> 2 files changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/src/passwd/getgrouplist.c b/src/passwd/getgrouplist.c
> index 43e5182..fd0bf5f 100644
> --- a/src/passwd/getgrouplist.c
> +++ b/src/passwd/getgrouplist.c
> @@ -17,7 +17,7 @@ int getgrouplist(const char *user, gid_t gid, gid_t *groups, int *ngroups)
> struct group *res;
> FILE *f;
> int swap = 0;
> - int32_t resp[INITGR_LEN];
> + int32_t resp[INITGR_LEN] = {0};
> uint32_t *nscdbuf = 0;
> char *buf = 0;
> char **mem = 0;
> diff --git a/src/passwd/nscd_query.c b/src/passwd/nscd_query.c
> index d38e371..8641e4f 100644
> --- a/src/passwd/nscd_query.c
> +++ b/src/passwd/nscd_query.c
> @@ -40,7 +40,13 @@ retry:
> buf[0] = NSCDVERSION;
>
> fd = socket(PF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);
> - if (fd < 0) return NULL;
> + if (fd < 0) {
> + if (errno == EACCES || errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT) {
> + errno = errno_save;
> + return fopen("/dev/null", "re");
> + }
> + return 0;
> + }
>
> if(!(f = fdopen(fd, "r"))) {
> close(fd);
> --
> 2.7.3
>
I just ran across this patch that got lost last year while looking at
the git history for src/passwd and seeing commit
39494a273eaa6b714e0fa0c59ce7a1f5fbc80a1e. Was there any further
progress or discussion on it I might be overlooking? I think the
concept looks right but I wonder if there's a good way to avoid the
spurious /dev/null access.
Rich
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