Date: Wed, 22 May 2024 17:38:08 GMT From: Marko Zec <zec@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 9629a4b6865c - stable/13 - fib_dxr: check if cached fib_data matches the new request in dxr_init() Message-ID: <202405221738.44MHc8Bc027232@gitrepo.freebsd.org>
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The branch stable/13 has been updated by zec: URL: https://cgit.FreeBSD.org/src/commit/?id=9629a4b6865c5c56804f79a62f45512b175776e2 commit 9629a4b6865c5c56804f79a62f45512b175776e2 Author: Marko Zec <zec@FreeBSD.org> AuthorDate: 2024-05-17 15:55:43 +0000 Commit: Marko Zec <zec@FreeBSD.org> CommitDate: 2024-05-22 17:37:31 +0000 fib_dxr: check if cached fib_data matches the new request in dxr_init() When calling dxr_init(), the FIB_ALGO infrastructure may provide a pointer to a previous dxr instance, which permits reuse of auxiliary dxr structures, i.e. incremental lookup structure updates. For dxr this is a crucial feature provided by FIB_ALGO, since dxr incremental updates are typically several orders of magnitude faster than full lookup table rebuilds. However, the auxiliary dxr structure caches a pointer to struct fib_data and relies upon it for performing incremental updates. Apparently, incremental rebuild requests from FIB_ALGO, i.e. a calls to dxr_init() with a pointer old_data set, may (under not yet fully understood circumstances) be invoked within a different fib_data context than the one cached in the previous version of dxr auxiliary structures. In such (rare) events, we ignore the offered old dxr context, and proceed with a full lookup structure rebuild instead of attempting an incremental one using a fib_data context which may or may not no longer be valid, and thus lead to a system crash. PR: 278422 MFC after: 1 week (cherry picked from commit 4ab122e8ef127d36d95f874e85600c36c87c8c22) --- sys/netinet/in_fib_dxr.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/sys/netinet/in_fib_dxr.c b/sys/netinet/in_fib_dxr.c index 82245ecf6e66..539d7fe6c96f 100644 --- a/sys/netinet/in_fib_dxr.c +++ b/sys/netinet/in_fib_dxr.c @@ -1139,7 +1139,8 @@ dxr_init(uint32_t fibnum, struct fib_data *fd, void *old_data, void **data) } /* Check whether we may reuse the old auxiliary structures */ - if (old_dxr != NULL && old_dxr->aux != NULL) { + if (old_dxr != NULL && old_dxr->aux != NULL && + old_dxr->aux->fd == fd) { da = old_dxr->aux; atomic_add_int(&da->refcnt, 1); } @@ -1275,7 +1276,7 @@ dxr_change_rib_batch(struct rib_head *rnh, struct fib_change_queue *q, da = dxr->aux; MPASS(da != NULL); - MPASS(da->fd != NULL); + MPASS(da->fd == dxr->fd); MPASS(da->refcnt > 0); FIB_PRINTF(LOG_INFO, da->fd, "processing %d update(s)", q->count);
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