fix: memory leak of nsgrp in src/useradd.c grp_update()

grp_update() also duplicates each shadow group with __sgr_dup() and
never frees the 'nsgrp' copy.  Release it with sgr_free().

valgrind --leak-check=full --show-leak-kinds=all \
    src/useradd -M -N -G grp1,...,grp10 alice, before this commit:

    691 (320 direct, 371 indirect) bytes in 10 blocks are definitely lost
       at 0x4848EB8: calloc
       by __sgr_dup (sgroupio.c:37)
       by grp_update (useradd.c:1104)
    definitely lost: 480 bytes in 30 blocks

after this commit:

    definitely lost: 160 bytes in 20 blocks

Signed-off-by: Artem Semenov <savoptik@altlinux.org>
Reviewed-by: Alejandro Colomar <alx@kernel.org>

diff --git a/src/useradd.c b/src/useradd.c
index e243c68570607622ab5903415bc4451c793f8351..25b7f4f3c9b0413251c4256d8e3bbcd050ecfae0 100644 (file)
--- a/src/useradd.c
+++ b/src/useradd.c
@@ -1125,6 +1125,7 @@ static void grp_update (bool process_selinux)
 #endif
                SYSLOG(LOG_INFO, "add '%s' to shadow group '%s'",
                       user_name, nsgrp->sg_namp);
 #endif
                SYSLOG(LOG_INFO, "add '%s' to shadow group '%s'",
                       user_name, nsgrp->sg_namp);

+               sgr_free (nsgrp);

        }
 #endif                         /* SHADOWGRP */
 }
        }
 #endif                         /* SHADOWGRP */
 }