Date: Wed, 24 Feb 2021 00:02:03 GMT From: "Jason A. Harmening" <jah@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 941747f63cfa - stable/12 - Fix divide-by-zero panic when ASLR is enabled and superpages disabled Message-ID: <202102240002.11O023wP020908@gitrepo.freebsd.org>
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The branch stable/12 has been updated by jah: URL: https://cgit.FreeBSD.org/src/commit/?id=941747f63cfa127248e6c7246f75c5ac5e142fcc commit 941747f63cfa127248e6c7246f75c5ac5e142fcc Author: Jason A. Harmening <jah@FreeBSD.org> AuthorDate: 2021-02-15 02:47:22 +0000 Commit: Jason A. Harmening <jah@FreeBSD.org> CommitDate: 2021-02-24 00:04:00 +0000 Fix divide-by-zero panic when ASLR is enabled and superpages disabled When locating the anonymous memory region for a vm_map with ASLR enabled, we try to keep the slid base address aligned on a superpage boundary to minimize pagetable fragmentation and maximize the potential usage of superpage mappings. We can't (portably) do this if superpages have been disabled by loader tunable and pagesizes[1] is 0, and it would be less beneficial in that case anyway. PR: 253511 (cherry picked from commit 41032835dc2d489ec7841d7529f74f6389329cd3) --- sys/kern/imgact_elf.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/sys/kern/imgact_elf.c b/sys/kern/imgact_elf.c index 18b83d6b499a..4c05be66e51f 100644 --- a/sys/kern/imgact_elf.c +++ b/sys/kern/imgact_elf.c @@ -1271,7 +1271,8 @@ __CONCAT(exec_, __elfN(imgact))(struct image_params *imgp) maxv1 = maxv / 2 + addr / 2; MPASS(maxv1 >= addr); /* No overflow */ map->anon_loc = __CONCAT(rnd_, __elfN(base))(map, addr, maxv1, - MAXPAGESIZES > 1 ? pagesizes[1] : pagesizes[0]); + (MAXPAGESIZES > 1 && pagesizes[1] != 0) ? + pagesizes[1] : pagesizes[0]); } else { map->anon_loc = addr; } @@ -1281,7 +1282,7 @@ __CONCAT(exec_, __elfN(imgact))(struct image_params *imgp) if (interp != NULL) { VOP_UNLOCK(imgp->vp, 0); if ((map->flags & MAP_ASLR) != 0) { - /* Assume that interpeter fits into 1/4 of AS */ + /* Assume that interpreter fits into 1/4 of AS */ maxv1 = maxv / 2 + addr / 2; MPASS(maxv1 >= addr); /* No overflow */ addr = __CONCAT(rnd_, __elfN(base))(map, addr,
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