BASH PATCH REPORT ================= Bash-Release: 4.4 Patch-ID: bash44-020 Bug-Reported-by: Graham Northup Bug-Reference-ID: <537530c3-61f0-349b-9de6-fa4e2487f428@clarkson.edu> Bug-Reference-URL: http://lists.gnu.org/archive/html/bug-bash/2017-02/msg00025.html Bug-Description: In circumstances involving long-running scripts that create and reap many processes, it is possible for the hash table bash uses to store exit statuses from asynchronous processes to develop loops. This patch fixes the loop causes and adds code to detect any future loops. Patch (apply with `patch -p0'): *** ../bash-4.4-patched/jobs.c 2016-11-11 13:42:55.000000000 -0500 --- jobs.c 2017-02-22 15:16:28.000000000 -0500 *************** *** 813,818 **** struct pidstat *ps; ! bucket = pshash_getbucket (pid); ! psi = bgp_getindex (); ps = &bgpids.storage[psi]; --- 796,815 ---- struct pidstat *ps; ! /* bucket == existing chain of pids hashing to same value ! psi = where were going to put this pid/status */ ! ! bucket = pshash_getbucket (pid); /* index into pidstat_table */ ! psi = bgp_getindex (); /* bgpids.head, index into storage */ ! ! /* XXX - what if psi == *bucket? */ ! if (psi == *bucket) ! { ! #ifdef DEBUG ! internal_warning ("hashed pid %d (pid %d) collides with bgpids.head, skipping", psi, pid); ! #endif ! bgpids.storage[psi].pid = NO_PID; /* make sure */ ! psi = bgp_getindex (); /* skip to next one */ ! } ! ps = &bgpids.storage[psi]; *************** *** 842,845 **** --- 839,843 ---- { struct pidstat *ps; + ps_index_t *bucket; ps = &bgpids.storage[psi]; *************** *** 847,856 **** return; ! if (ps->bucket_next != NO_PID) bgpids.storage[ps->bucket_next].bucket_prev = ps->bucket_prev; ! if (ps->bucket_prev != NO_PID) bgpids.storage[ps->bucket_prev].bucket_next = ps->bucket_next; else ! *(pshash_getbucket (ps->pid)) = ps->bucket_next; } --- 845,861 ---- return; ! if (ps->bucket_next != NO_PIDSTAT) bgpids.storage[ps->bucket_next].bucket_prev = ps->bucket_prev; ! if (ps->bucket_prev != NO_PIDSTAT) bgpids.storage[ps->bucket_prev].bucket_next = ps->bucket_next; else ! { ! bucket = pshash_getbucket (ps->pid); ! *bucket = ps->bucket_next; /* deleting chain head in hash table */ ! } ! ! /* clear out this cell, just in case */ ! ps->pid = NO_PID; ! ps->bucket_next = ps->bucket_prev = NO_PIDSTAT; } *************** *** 859,863 **** pid_t pid; { ! ps_index_t psi; if (bgpids.storage == 0 || bgpids.nalloc == 0 || bgpids.npid == 0) --- 864,868 ---- pid_t pid; { ! ps_index_t psi, orig_psi; if (bgpids.storage == 0 || bgpids.nalloc == 0 || bgpids.npid == 0) *************** *** 865,871 **** /* Search chain using hash to find bucket in pidstat_table */ ! for (psi = *(pshash_getbucket (pid)); psi != NO_PIDSTAT; psi = bgpids.storage[psi].bucket_next) ! if (bgpids.storage[psi].pid == pid) ! break; if (psi == NO_PIDSTAT) --- 870,883 ---- /* Search chain using hash to find bucket in pidstat_table */ ! for (orig_psi = psi = *(pshash_getbucket (pid)); psi != NO_PIDSTAT; psi = bgpids.storage[psi].bucket_next) ! { ! if (bgpids.storage[psi].pid == pid) ! break; ! if (orig_psi == bgpids.storage[psi].bucket_next) /* catch reported bug */ ! { ! internal_warning ("bgp_delete: LOOP: psi (%d) == storage[psi].bucket_next", psi); ! return 0; ! } ! } if (psi == NO_PIDSTAT) *************** *** 905,909 **** pid_t pid; { ! ps_index_t psi; if (bgpids.storage == 0 || bgpids.nalloc == 0 || bgpids.npid == 0) --- 917,921 ---- pid_t pid; { ! ps_index_t psi, orig_psi; if (bgpids.storage == 0 || bgpids.nalloc == 0 || bgpids.npid == 0) *************** *** 911,917 **** /* Search chain using hash to find bucket in pidstat_table */ ! for (psi = *(pshash_getbucket (pid)); psi != NO_PIDSTAT; psi = bgpids.storage[psi].bucket_next) ! if (bgpids.storage[psi].pid == pid) ! return (bgpids.storage[psi].status); return -1; --- 923,936 ---- /* Search chain using hash to find bucket in pidstat_table */ ! for (orig_psi = psi = *(pshash_getbucket (pid)); psi != NO_PIDSTAT; psi = bgpids.storage[psi].bucket_next) ! { ! if (bgpids.storage[psi].pid == pid) ! return (bgpids.storage[psi].status); ! if (orig_psi == bgpids.storage[psi].bucket_next) /* catch reported bug */ ! { ! internal_warning ("bgp_search: LOOP: psi (%d) == storage[psi].bucket_next", psi); ! return -1; ! } ! } return -1; *** ../bash-4.4/patchlevel.h 2016-06-22 14:51:03.000000000 -0400 --- patchlevel.h 2016-10-01 11:01:28.000000000 -0400 *************** *** 26,30 **** looks for to find the patch level (for the sccs version string). */ ! #define PATCHLEVEL 19 #endif /* _PATCHLEVEL_H_ */ --- 26,30 ---- looks for to find the patch level (for the sccs version string). */ ! #define PATCHLEVEL 20 #endif /* _PATCHLEVEL_H_ */