Nicolas Iooss <nicolas.iooss@xxxxxxx> writes:
On Wed, Feb 6, 2019 at 8:45 PM Petr Lautrbach
<plautrba@xxxxxxxxxx> wrote:
getgrnam_r() uses a preallocated buffer to store a structure
containing
the broken-out fields of the record in the group database. The
size of
this buffer is usually sysconf(_SC_GETGR_R_SIZE_MAX) == 1024
and it is
not enough for groups with a large number of users. In these
cases,
getgrnam_r() returns -1 and sets errno to ERANGE and the caller
can
retry with a larger buffer.
Fixes:
$ semanage login -a -s user_u -r s0-s0:c1.c2 '%largegroup'
libsemanage.semanage_direct_commit: semanage_genhomedircon
returned error code -1. (Numerical result out of range).
OSError: Numerical result out of range
Signed-off-by: Petr Lautrbach <plautrba@xxxxxxxxxx>
---
libsemanage/src/genhomedircon.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/libsemanage/src/genhomedircon.c
b/libsemanage/src/genhomedircon.c
index 591941fb..ac376671 100644
--- a/libsemanage/src/genhomedircon.c
+++ b/libsemanage/src/genhomedircon.c
@@ -1077,10 +1077,20 @@ static int
get_group_users(genhomedircon_settings_t * s,
const char *grname = selogin + 1;
- if (getgrnam_r(grname, &grstorage, grbuf,
- (size_t) grbuflen, &group) != 0) {
- goto cleanup;
+ errno = 0;
+ while (
+ (retval = getgrnam_r(grname, &grstorage, grbuf,
(size_t) grbuflen, &group)) != 0 &&
+ errno == ERANGE
+ ) {
+ char *new_grbuf;
+ grbuflen *= 2;
+ new_grbuf = realloc(grbuf, grbuflen);
+ if (new_grbuf == NULL)
+ goto cleanup;
+ grbuf = new_grbuf;
}
Hello,
When reading this for loop, I am concerned about the case where
the
member list exceeds 2Go on a system with a 32-bit CPU (where
sizeof(long) = 4). Even if it seems very unlikely, if this ever
happens, the loop will become infinite. Would you agree with
adding
"&& grbuflen > 0" to the condition of the while statement?
Makes sense, I'll add it. Thanks.
Anyway, if you do not agree, this patch looks good to me.
Acked-by: Nicolas Iooss <nicolas.iooss@xxxxxxx>
Thanks,
Nicolas
+ if (retval == -1)
+ goto cleanup;
According to the man page this check is not correct. - "In case of
error, an error number is returned, and NULL is stored in
*result."
I'll fix it as well.
if (group == NULL) {
ERR(s->h_semanage, "Can't find group named
%s\n", grname);
--
2.20.1
