From nobody Mon Apr 07 12:01:21 2025 X-Original-To: dev-commits-src-main@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 4ZWSV96BvTz5t9w4; Mon, 07 Apr 2025 12:01:21 +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 "R10" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4ZWSV94xGfz3vNm; Mon, 07 Apr 2025 12:01:21 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1744027281; 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=ZZSJpdvI9TgPPlRKD1qTZANbllUPT6aXmp+L0mVTRK8=; b=xfl9ZpBExc/DXRoPOmr7IAX3Tqsd8LbxF5gp33YZ1MAdD9qdNXI4eSgq5myq9ZmoUgevDb ZFIns1aGM0m084WpWTkgoLkcSIu9+N6lHWtFLuXkruoVMQ/9S3IM+amPnm52CU7F+NZ9op le3Q09oKWEtqH4JEfSMd9GP2RFJUNDuvsbvgkB0Z8Yi+5CmQBKkOnA0dVNhF3R8FvGtUs1 AVZn1PmvGjnef7dggYEr0mjuEYG2BiuPMCKIEQ1coCI7l5FRcSrVElf+pi3Kth8LnZxsAj 1GAtj5B8aLquHq91FW3iwpepG41SJTxyoJ/m8F8Qg52PJ8YSQzB0ZSV8O/vA8A== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1744027281; a=rsa-sha256; cv=none; b=Ded5ghNXMOcFpOB6SwttJiErUCh7dwM++fOymYoAqRiIRhrUySbh7uQTwYjZVNXstzyDfJ bsBqOWOH3BeczTX+2hKVMpTL2+pJRz31674k1UMD/am+AU4+lkha31M4aT12qg7MmtLwcb 4RU5JNnhwwv06ptNHf7/+H+RLo3DfKVLFvVxUMbsEeaBQGU2B/m8U+uh8aQXwhH020LVjO /r7IpnSv5L57Jn34TE5GsASeKMiAqEiO7TXrDxicjwaVuoSyukpicJeY7/aDNTUmqgeBJt OMGHdEVZZEmpOZDgbjpoZGf/3K8u4/HIwWTsYOSrCsj52neu0c/I/Fu5YUwZzA== 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=1744027281; 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=ZZSJpdvI9TgPPlRKD1qTZANbllUPT6aXmp+L0mVTRK8=; b=fcXC+4OGFq7/EdNnbA0Iz8KfVRCLsfz6oHgNpyouXeKDiMIzef0OKfb5Pf0L+n5nD+ZOm5 81Vpc/K2vKIGsMASTz9xf3qS8jGRHYdK709NeU18bQBIZXe3V+2Gn7n6ZVGm+RB7TVUAPb hz5eXPiiMmiI3+cGtrmSzjrYA1xMuMr13dmqae7GmsYvFGJRNHJxzG/jLdhto1Kgo0MOau z0hLD6rbcHHwgPQgbeJXObjUCasfYifpIxS8nDFSs5Z3SCslNOD+LrMzEPe1oBDXoWg1+a LKHwAnUAgl1ERobn40eNJhbSU2WXlmAkn5pTrHrHugBiGh/pR5Yw6gJKNq5KjQ== Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (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 did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 4ZWSV94TW8zmMQ; Mon, 07 Apr 2025 12:01:21 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.18.1/8.18.1) with ESMTP id 537C1L8m049476; Mon, 7 Apr 2025 12:01:21 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.18.1/8.18.1/Submit) id 537C1La5049473; Mon, 7 Apr 2025 12:01:21 GMT (envelope-from git) Date: Mon, 7 Apr 2025 12:01:21 GMT Message-Id: <202504071201.537C1La5049473@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org From: Mark Johnston Subject: git: 82d8c609cfb7 - main - posixshm: Fix range locking in shm_write() List-Id: Commit messages for the main branch of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-main List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: dev-commits-src-main@freebsd.org Sender: owner-dev-commits-src-main@FreeBSD.org 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: 82d8c609cfb7c6d8a9da8e30efa54240f293359e Auto-Submitted: auto-generated The branch main has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=82d8c609cfb7c6d8a9da8e30efa54240f293359e commit 82d8c609cfb7c6d8a9da8e30efa54240f293359e Author: Mark Johnston AuthorDate: 2025-04-06 22:51:53 +0000 Commit: Mark Johnston CommitDate: 2025-04-07 11:59:57 +0000 posixshm: Fix range locking in shm_write() There is a somewhat strange case where when writing to a POSIX shm object, the object is not allowed to grow, and the I/O offset+length overflows. In that case we simply truncate the I/O to the object size. Later we write-lock the range [offset, objsize). However, we were not checking whether offset > objsize, in which case we're writing zero bytes but locking an invalid range. Modify the range locking in shm_write() to take this possibility into account. While here, rename a variable to make its purpose a bit more clear, and add an assertion against negative offsets (which is supposed to be enforced by the caller of fo_write for I/O to files that aren't character devices). Reported by: syzkaller Reviewed by: kevans, kib MFC after: 2 weeks Differential Revision: https://reviews.freebsd.org/D49673 --- sys/kern/uipc_shm.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/sys/kern/uipc_shm.c b/sys/kern/uipc_shm.c index b4016e9dd6bf..7004e4f1c6ea 100644 --- a/sys/kern/uipc_shm.c +++ b/sys/kern/uipc_shm.c @@ -481,7 +481,10 @@ shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, struct shmfd *shmfd; void *rl_cookie; int error; - off_t size; + off_t newsize; + + KASSERT((flags & FOF_OFFSET) == 0 || uio->uio_offset >= 0, + ("%s: negative offset", __func__)); shmfd = fp->f_data; #ifdef MAC @@ -503,21 +506,23 @@ shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, return (EFBIG); } - size = shmfd->shm_size; + newsize = atomic_load_64(&shmfd->shm_size); } else { - size = uio->uio_offset + uio->uio_resid; + newsize = uio->uio_offset + uio->uio_resid; } if ((flags & FOF_OFFSET) == 0) rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX); else - rl_cookie = shm_rangelock_wlock(shmfd, uio->uio_offset, size); + rl_cookie = shm_rangelock_wlock(shmfd, uio->uio_offset, + MAX(newsize, uio->uio_offset)); if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) { error = EPERM; } else { error = 0; if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0 && - size > shmfd->shm_size) { - error = shm_dotruncate_cookie(shmfd, size, rl_cookie); + newsize > shmfd->shm_size) { + error = shm_dotruncate_cookie(shmfd, newsize, + rl_cookie); } if (error == 0) error = uiomove_object(shmfd->shm_object,