From nobody Tue Aug 25 15:59:25 2026 X-Original-To: dev-commits-src-all@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4hTssn72Bdz6pbDX for ; Tue, 25 Aug 2026 15:59:25 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "YR2" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4hTssn38ctz41YG for ; Tue, 25 Aug 2026 15:59:25 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1787673565; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=n14TCD1COwRU+xcBT4by+pBMwt566sugHSqOxFOdhdA=; b=BWzAzMuwt4D6GjwwDc7mXwv2Vnwux2/eSwg5oAFEr8nfXq/x6Tnt17PurFQnuEckvDwkCg MU2GKVWlZm9tP0R81OLKfFprWqydh2lQQy9vhZtf6FYMMEbIYfy9iF8JhM5drYTZFP0cLz +EhqVAPAR8YFz3QaqI8DtexMQ+cuVPB9kzNXbTXO3lzrZPhfdJ/rrFhmTgTKPsmLqXkSoS w7nvKSXSGcVTWuYQ10vTYmXEES6i87rDlXmyuyerkUejwLraXkIdEjGRIOh+bVf8VhU/QK Gf7A7VqPG9jxtSiURqBtncUPhqSGSU0u1iN/US98iKlhRw53mVmkGL056fj3xQ== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1787673565; a=rsa-sha256; cv=none; b=m2xmA1UKWaigKGKbDLn73Nio/9ypwS1d3KOja7KVl0JR/y2D9EIr54jMbyCq61Uz81pH1t 324j/tjZnGSwpSz87T6wH5T6IapKeiami0mz4ra1t/8glsxX06zRB/apaPqBghQN/ycnF2 3h45CpfW6KDpm+dmPFSiGazE7gp2OLhnsdFZOA08vpI+tQ0cUtd/ZoUdj5cV03Kg8C/Zls fNmZ98mAXDBbojkmXGaa9+7liv3zaJWDSFSKIY3nOocPPAEkiwChJXUXMCNdn3TxIieDIr JWMCPxUlYZC5I7QaB+AT5lENq0qA6b731KXl5rTmar9aDgLemM/0WQS17+ehHg== ARC-Authentication-Results: i=1; mx1.freebsd.org; none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1787673565; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=n14TCD1COwRU+xcBT4by+pBMwt566sugHSqOxFOdhdA=; b=m0uoI+uiz0IxoAY96Tdeh82x1xjrs1KUify0CeJo09GPqCTR8zfhEDcdkeQgZAWLiHY3ae kzfG3bk4R2DSWSA5M6OGktDVpht/O406IuRoef+ECUaP0FKsUotMgSAEQq8w9jnUOPlTXc xt08cjZqDQCKiSK99rKgiKZtgXL1QKkiOd80QnSVuiyjw6pcgcFb/FIelBuks1kGZSTwsH a/l68L22rOTNAGwnH5o6tZ+lt9PXQ2LyJg+EBtU/jjcE6+88Ik7dDqoX6zMGdSUEt6TynA ljeTI2gA6i9QXzJUVAZeVIY5GgnrkVhOzgXVFMU7CJ+WkadaiXp19HTSfKkwKA== Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) by mxrelay.nyi.freebsd.org (Postfix) with ESMTP id 4hTssn1Xf4zy5y for ; Tue, 25 Aug 2026 15:59:25 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from git (uid 1279) (envelope-from git@FreeBSD.org) id 314c0 by gitrepo.freebsd.org (DragonFly Mail Agent v0.13+ on gitrepo.freebsd.org); Tue, 25 Aug 2026 15:59:25 +0000 To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org From: Mark Johnston Subject: git: b13a7008282a - main - posixshm: Fix a TOCTOU race in the FIOSSHMLPGCNF handler List-Id: Commit messages for all branches of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-all List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: dev-commits-src-all@freebsd.org Sender: owner-dev-commits-src-all@FreeBSD.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: markj X-Git-Repository: src X-Git-Refname: refs/heads/main X-Git-Reftype: branch X-Git-Commit: b13a7008282aaa34e7021ac7b961600dbbc28bf3 Auto-Submitted: auto-generated Date: Tue, 25 Aug 2026 15:59:25 +0000 Message-Id: <6a8dbbdd.314c0.3437eab7@gitrepo.freebsd.org> The branch main has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=b13a7008282aaa34e7021ac7b961600dbbc28bf3 commit b13a7008282aaa34e7021ac7b961600dbbc28bf3 Author: Mark Johnston AuthorDate: 2026-08-24 18:15:38 +0000 Commit: Mark Johnston CommitDate: 2026-08-25 15:46:24 +0000 posixshm: Fix a TOCTOU race in the FIOSSHMLPGCNF handler The check for whether shm_lp_psind was assigned was unlocked. This race can be exploited to create an object with psind==2 but with only pagesizes[1] worth of pages populated. This in turn can be used to escalate privileges. Fix this by acquiring the rangelock earlier. In shm_mmap_large(), assert that we hold the rangelock. In shm_write(), annotate an unlocked load of shm_lp_psind. Approved by: so Security: FreeBSD-SA-26:63.posixshm Security: CVE-2026-58094 Reported by: tsune of GMO Cybersecurity by Ierae, Inc. working with TrendAI Zero Day Initiative Reviewed by: kib Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D59104 --- sys/kern/uipc_shm.c | 27 +++++++++++++++++---------- sys/sys/mman.h | 2 +- 2 files changed, 18 insertions(+), 11 deletions(-) diff --git a/sys/kern/uipc_shm.c b/sys/kern/uipc_shm.c index 04b6f4f6e07a..067a628fdab0 100644 --- a/sys/kern/uipc_shm.c +++ b/sys/kern/uipc_shm.c @@ -512,8 +512,6 @@ shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, if (error) return (error); #endif - if (shm_largepage(shmfd) && shmfd->shm_lp_psind == 0) - return (EINVAL); foffset_lock_uio(fp, uio, flags); if (uio->uio_resid > OFF_MAX - uio->uio_offset) { /* @@ -535,7 +533,9 @@ shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, else rl_cookie = shm_rangelock_wlock(shmfd, uio->uio_offset, MAX(newsize, uio->uio_offset)); - if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) { + if (shm_largepage(shmfd) && shmfd->shm_lp_psind == 0) { + error = EINVAL; + } else if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) { error = EPERM; } else { error = 0; @@ -592,18 +592,23 @@ shm_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred, if (!shm_largepage(shmfd)) return (ENOTTY); conf = data; + rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX); if (shmfd->shm_lp_psind != 0 && - conf->psind != shmfd->shm_lp_psind) + conf->psind != shmfd->shm_lp_psind) { + shm_rangelock_unlock(shmfd, rl_cookie); return (EINVAL); + } if (conf->psind <= 0 || conf->psind >= MAXPAGESIZES || - pagesizes[conf->psind] == 0) + pagesizes[conf->psind] == 0) { + shm_rangelock_unlock(shmfd, rl_cookie); return (EINVAL); + } if (conf->alloc_policy != SHM_LARGEPAGE_ALLOC_DEFAULT && conf->alloc_policy != SHM_LARGEPAGE_ALLOC_NOWAIT && - conf->alloc_policy != SHM_LARGEPAGE_ALLOC_HARD) + conf->alloc_policy != SHM_LARGEPAGE_ALLOC_HARD) { + shm_rangelock_unlock(shmfd, rl_cookie); return (EINVAL); - - rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX); + } shmfd->shm_lp_psind = conf->psind; shmfd->shm_lp_alloc_policy = conf->alloc_policy; shmfd->shm_object->un_pager.phys.data_val = conf->psind; @@ -1571,7 +1576,7 @@ out: static int shm_mmap_large(struct shmfd *shmfd, vm_map_t map, vm_offset_t *addr, vm_size_t size, vm_prot_t prot, vm_prot_t max_prot, int flags, - vm_ooffset_t foff, struct thread *td) + vm_ooffset_t foff, struct thread *td, void *rl_cookie) { struct vmspace *vms; vm_map_entry_t next_entry, prev_entry; @@ -1579,6 +1584,8 @@ shm_mmap_large(struct shmfd *shmfd, vm_map_t map, vm_offset_t *addr, int docow, error, rv, try; bool curmap; + rangelock_cookie_assert(rl_cookie, RA_LOCKED); + if (shmfd->shm_lp_psind == 0) return (EINVAL); @@ -1754,7 +1761,7 @@ shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize, if (shm_largepage(shmfd)) { writecnt = false; error = shm_mmap_large(shmfd, map, addr, objsize, prot, - maxprot, flags, foff, td); + maxprot, flags, foff, td, rl_cookie); } else { if (writecnt) { vm_pager_update_writecount(shmfd->shm_object, 0, diff --git a/sys/sys/mman.h b/sys/sys/mman.h index ba478bc71c7c..e15cc4380b5b 100644 --- a/sys/sys/mman.h +++ b/sys/sys/mman.h @@ -293,7 +293,7 @@ struct shmfd { int shm_flags; int shm_seals; - /* largepage config */ + /* largepage config, synchronized by the rangelock */ int shm_lp_psind; int shm_lp_alloc_policy; };