From 5dc6af0eec29b119b731c793037fd77214fc9438 Mon Sep 17 00:00:00 2001 From: Brian Behlendorf Date: Tue, 19 Mar 2013 12:05:08 -0700 Subject: [PATCH] Add zio_ddt_free()+ddt_phys_decref() error handling The assumption in zio_ddt_free() is that ddt_phys_select() must always find a match. However, if that fails due to a damaged DDT or some other reason the code will NULL dereference in ddt_phys_decref(). While this should never happen it has been observed on various platforms. The result is that unless your willing to patch the ZFS code the pool is inaccessible. Therefore, we're choosing to more gracefully handle this case rather than leave it fatal. http://mail.opensolaris.org/pipermail/zfs-discuss/2012-February/050972.html Signed-off-by: Brian Behlendorf Closes #1308 --- module/zfs/ddt.c | 6 ++++-- module/zfs/zio.c | 7 +++++-- 2 files changed, 9 insertions(+), 4 deletions(-) diff --git a/module/zfs/ddt.c b/module/zfs/ddt.c index ef868619a..2d8763a54 100644 --- a/module/zfs/ddt.c +++ b/module/zfs/ddt.c @@ -323,8 +323,10 @@ ddt_phys_addref(ddt_phys_t *ddp) void ddt_phys_decref(ddt_phys_t *ddp) { - ASSERT((int64_t)ddp->ddp_refcnt > 0); - ddp->ddp_refcnt--; + if (ddp) { + ASSERT((int64_t)ddp->ddp_refcnt > 0); + ddp->ddp_refcnt--; + } } void diff --git a/module/zfs/zio.c b/module/zfs/zio.c index 77b1764d7..0622553f5 100644 --- a/module/zfs/zio.c +++ b/module/zfs/zio.c @@ -2249,8 +2249,11 @@ zio_ddt_free(zio_t *zio) ddt_enter(ddt); freedde = dde = ddt_lookup(ddt, bp, B_TRUE); - ddp = ddt_phys_select(dde, bp); - ddt_phys_decref(ddp); + if (dde) { + ddp = ddt_phys_select(dde, bp); + if (ddp) + ddt_phys_decref(ddp); + } ddt_exit(ddt); return (ZIO_PIPELINE_CONTINUE);