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 | 20 +++++++++++++++++---
1 file changed, 17 insertions(+), 3 deletions(-)
diff --git a/libsemanage/src/genhomedircon.c b/libsemanage/src/genhomedircon.c
index 591941fb..e5f8d371 100644
--- a/libsemanage/src/genhomedircon.c
+++ b/libsemanage/src/genhomedircon.c
@@ -1077,10 +1077,24 @@ 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;
+ if (grbuflen < 0)
+ /* the member list could exceed 2Gb on a system with a 32-bit CPU (where
+ * sizeof(long) = 4) - if this ever happened, the loop would become infinite. */
+ goto cleanup;
+ new_grbuf = realloc(grbuf, grbuflen);
+ if (new_grbuf == NULL)
+ goto cleanup;
+ grbuf = new_grbuf;
}
+ if (retval != 0)
+ goto cleanup;
if (group == NULL) {
ERR(s->h_semanage, "Can't find group named %s\n", grname);
--
2.20.1
