Author: rlibby Date: Wed Nov 27 19:49:55 2019 New Revision: 355137 URL: https://svnweb.freebsd.org/changeset/base/355137
Log: uma: trash memory when ctor/dtor supplied too On INVARIANTS kernels, UMA has a use-after-free detection mechanism. This mechanism previously required that all of the ctor/dtor/uminit/fini arguments to uma_zcreate() be NULL in order to function. Now, it only requires that uminit and fini be NULL; now, the trash ctor and dtor will be called in addition to any supplied ctor or dtor. Also do a little refactoring for readability of the resulting logic. This enables use-after-free detection for more zones, and will allow for simplification of some callers that worked around the previous restriction (see kern_mbuf.c). Reviewed by: jeff, markj Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D20722 Modified: head/sys/vm/uma_core.c head/sys/vm/uma_int.h Modified: head/sys/vm/uma_core.c ============================================================================== --- head/sys/vm/uma_core.c Wed Nov 27 19:34:33 2019 (r355136) +++ head/sys/vm/uma_core.c Wed Nov 27 19:49:55 2019 (r355137) @@ -1869,6 +1869,11 @@ zone_ctor(void *mem, int size, void *udata, int flags) for (i = 0; i < vm_ndomains; i++) TAILQ_INIT(&zone->uz_domain[i].uzd_buckets); +#ifdef INVARIANTS + if (arg->uminit == trash_init && arg->fini == trash_fini) + zone->uz_flags |= UMA_ZFLAG_TRASH; +#endif + /* * This is a pure cache zone, no kegs. */ @@ -2302,14 +2307,17 @@ uma_zcreate(const char *name, size_t size, uma_ctor ct args.fini = fini; #ifdef INVARIANTS /* - * If a zone is being created with an empty constructor and - * destructor, pass UMA constructor/destructor which checks for - * memory use after free. + * Inject procedures which check for memory use after free if we are + * allowed to scramble the memory while it is not allocated. This + * requires that: UMA is actually able to access the memory, no init + * or fini procedures, no dependency on the initial value of the + * memory, and no (legitimate) use of the memory after free. Note, + * the ctor and dtor do not need to be empty. + * + * XXX UMA_ZONE_OFFPAGE. */ if ((!(flags & (UMA_ZONE_ZINIT | UMA_ZONE_NOFREE))) && - ctor == NULL && dtor == NULL && uminit == NULL && fini == NULL) { - args.ctor = trash_ctor; - args.dtor = trash_dtor; + uminit == NULL && fini == NULL) { args.uminit = trash_init; args.fini = trash_fini; } @@ -2462,15 +2470,14 @@ static void * item_ctor(uma_zone_t zone, void *udata, int flags, void *item) { #ifdef INVARIANTS - int skipdbg; + bool skipdbg; skipdbg = uma_dbg_zskip(zone, item); - if (zone->uz_ctor != NULL && - (!skipdbg || zone->uz_ctor != trash_ctor || - zone->uz_dtor != trash_dtor) && -#else - if (__predict_false(zone->uz_ctor != NULL) && + if (!skipdbg && (zone->uz_flags & UMA_ZFLAG_TRASH) != 0 && + zone->uz_ctor != trash_ctor) + trash_ctor(item, zone->uz_size, udata, flags); #endif + if (__predict_false(zone->uz_ctor != NULL) && zone->uz_ctor(item, zone->uz_size, udata, flags) != 0) { counter_u64_add(zone->uz_fails, 1); zone_free_item(zone, item, udata, SKIP_DTOR | SKIP_CNT); @@ -2486,6 +2493,31 @@ item_ctor(uma_zone_t zone, void *udata, int flags, voi return (item); } +static inline void +item_dtor(uma_zone_t zone, void *item, void *udata, enum zfreeskip skip) +{ +#ifdef INVARIANTS + bool skipdbg; + + skipdbg = uma_dbg_zskip(zone, item); + if (skip == SKIP_NONE && !skipdbg) { + if ((zone->uz_flags & UMA_ZONE_MALLOC) != 0) + uma_dbg_free(zone, udata, item); + else + uma_dbg_free(zone, NULL, item); + } +#endif + if (skip < SKIP_DTOR) { + if (zone->uz_dtor != NULL) + zone->uz_dtor(item, zone->uz_size, udata); +#ifdef INVARIANTS + if (!skipdbg && (zone->uz_flags & UMA_ZFLAG_TRASH) != 0 && + zone->uz_dtor != trash_dtor) + trash_dtor(item, zone->uz_size, udata); +#endif + } +} + /* See uma.h */ void * uma_zalloc_arg(uma_zone_t zone, void *udata, int flags) @@ -2523,6 +2555,7 @@ uma_zalloc_arg(uma_zone_t zone, void *udata, int flags if (zone->uz_ctor != NULL && zone->uz_ctor(item, zone->uz_size, udata, flags) != 0) { + counter_u64_add(zone->uz_fails, 1); zone->uz_fini(item, zone->uz_size); return (NULL); } @@ -3131,9 +3164,6 @@ uma_zfree_arg(uma_zone_t zone, void *item, void *udata int itemdomain; #endif bool lockfail; -#ifdef INVARIANTS - bool skipdbg; -#endif /* Enable entropy collection for RANDOM_ENABLE_UMA kernel option */ random_harvest_fast_uma(&zone, sizeof(zone), RANDOM_UMA); @@ -3157,20 +3187,7 @@ uma_zfree_arg(uma_zone_t zone, void *item, void *udata return; } #endif -#ifdef INVARIANTS - skipdbg = uma_dbg_zskip(zone, item); - if (skipdbg == false) { - if (zone->uz_flags & UMA_ZONE_MALLOC) - uma_dbg_free(zone, udata, item); - else - uma_dbg_free(zone, NULL, item); - } - if (zone->uz_dtor != NULL && (!skipdbg || - zone->uz_dtor != trash_dtor || zone->uz_ctor != trash_ctor)) -#else - if (zone->uz_dtor != NULL) -#endif - zone->uz_dtor(item, zone->uz_size, udata); + item_dtor(zone, item, udata, SKIP_NONE); /* * The race here is acceptable. If we miss it we'll just have to wait @@ -3459,24 +3476,8 @@ zone_release(uma_zone_t zone, void **bucket, int cnt) static void zone_free_item(uma_zone_t zone, void *item, void *udata, enum zfreeskip skip) { -#ifdef INVARIANTS - bool skipdbg; - skipdbg = uma_dbg_zskip(zone, item); - if (skip == SKIP_NONE && !skipdbg) { - if (zone->uz_flags & UMA_ZONE_MALLOC) - uma_dbg_free(zone, udata, item); - else - uma_dbg_free(zone, NULL, item); - } - - if (skip < SKIP_DTOR && zone->uz_dtor != NULL && - (!skipdbg || zone->uz_dtor != trash_dtor || - zone->uz_ctor != trash_ctor)) -#else - if (skip < SKIP_DTOR && zone->uz_dtor != NULL) -#endif - zone->uz_dtor(item, zone->uz_size, udata); + item_dtor(zone, item, udata, skip); if (skip < SKIP_FINI && zone->uz_fini) zone->uz_fini(item, zone->uz_size); Modified: head/sys/vm/uma_int.h ============================================================================== --- head/sys/vm/uma_int.h Wed Nov 27 19:34:33 2019 (r355136) +++ head/sys/vm/uma_int.h Wed Nov 27 19:49:55 2019 (r355137) @@ -389,6 +389,7 @@ struct uma_zone { #define UMA_ZFLAG_RECLAIMING 0x08000000 /* Running zone_reclaim(). */ #define UMA_ZFLAG_BUCKET 0x10000000 /* Bucket zone. */ #define UMA_ZFLAG_INTERNAL 0x20000000 /* No offpage no PCPU. */ +#define UMA_ZFLAG_TRASH 0x40000000 /* Add trash ctor/dtor. */ #define UMA_ZFLAG_CACHEONLY 0x80000000 /* Don't ask VM for buckets. */ #define UMA_ZFLAG_INHERIT \ _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
