From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AIpwx48eHXcw6iKaMsNVaFY1GNRllAwB+Kq9UHF0FZLg9Mb9CXfeZHnG6J7s/2wve6vn3mbRN/zp ARC-Seal: i=1; a=rsa-sha256; t=1522168919; cv=none; d=google.com; s=arc-20160816; b=ME2oq2ixwDAL7NNloA7L3e2uQpHfcuAUwdbccpTywFRtmVh7PXflC0jjNUbYXp2d0+ JN19oqj5CoRgN+QcSBsic9V37a0UZOXzMI5kSRWGPkvULWPq/Tk1cibr7rAYRfkYRh14 bwCnvp30tHhMfrsrncN2yNN9zWO5Qb8ZGkv67ydT6LQA/IJ5vNzL9OIbxgPe3Nm8y3Ps vEV+ljwjm2cKh4N+0EJIn9i3CllWFEJS527F3YZ+JR2EVQF3+HsPLkaU7aYerVn0c7Cf pJ/q0qBG8ll2iT1nQ3fv6apg/hEZ69u8DsBAL9S0JZAPbQB0RV5P475G8LdB+k3hmwrL XX5w== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=wpS64qIxKVH8UdzeCrXxiMb0y3cJ14KAwJCUjqrw6DM=; b=yOcdcr2ittSlPc49q8qCLfc6sGYymzEzHeXEV5dCjZyeed7I3+j+2RKloLZVMI3FM3 pzSYjcNHe/6hYKnRLxEKW2JZ36qd3lxNpFQc8jCWDIImmGlCyCu6960kP8j6LN4Fc8fW plMUbW3d/tis2zCMvyMJEkHs0lvo+8nOaEUDkuoYRll6DwYSXm3zOHtOjY5TaG4P0pRg unaYoKzj4cJpEH1I7Fv8wjNEfNUhj17otO2/X7Tg3F1+YXQzwaTenGD8NJDnTQXitCNA E7nfMz0K67ttSGNibD4VMPfpBFR6m6UZx1GqlnglqoW+DFS6N5f7mjfx34xX9OE5+85C EUhg== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.61.202 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.61.202 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+1ff6f9fcc3c35f1c72a95e26528c8e7e3276e4da@syzkaller.appspotmail.com, Eric Biggers , Tejun Heo Subject: [PATCH 4.15 034/105] libata: fix length validation of ATAPI-relayed SCSI commands Date: Tue, 27 Mar 2018 18:27:14 +0200 Message-Id: <20180327162759.438327189@linuxfoundation.org> X-Mailer: git-send-email 2.16.3 In-Reply-To: <20180327162757.813009222@linuxfoundation.org> References: <20180327162757.813009222@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1596109044007210332?= X-GMAIL-MSGID: =?utf-8?q?1596109796531570445?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Biggers commit 058f58e235cbe03e923b30ea7c49995a46a8725f upstream. syzkaller reported a crash in ata_bmdma_fill_sg() when writing to /dev/sg1. The immediate cause was that the ATA command's scatterlist was not DMA-mapped, which causes 'pi - 1' to underflow, resulting in a write to 'qc->ap->bmdma_prd[0xffffffff]'. Strangely though, the flag ATA_QCFLAG_DMAMAP was set in qc->flags. The root cause is that when __ata_scsi_queuecmd() is preparing to relay a SCSI command to an ATAPI device, it doesn't correctly validate the CDB length before copying it into the 16-byte buffer 'cdb' in 'struct ata_queued_cmd'. Namely, it validates the fixed CDB length expected based on the SCSI opcode but not the actual CDB length, which can be larger due to the use of the SG_NEXT_CMD_LEN ioctl. Since 'flags' is the next member in ata_queued_cmd, a buffer overflow corrupts it. Fix it by requiring that the actual CDB length be <= 16 (ATAPI_CDB_LEN). [Really it seems the length should be required to be <= dev->cdb_len, but the current behavior seems to have been intentionally introduced by commit 607126c2a21c ("libata-scsi: be tolerant of 12-byte ATAPI commands in 16-byte CDBs") to work around a userspace bug in mplayer. Probably the workaround is no longer needed (mplayer was fixed in 2007), but continuing to allow lengths to up 16 appears harmless for now.] Here's a reproducer that works in QEMU when /dev/sg1 refers to the CD-ROM drive that qemu-system-x86_64 creates by default: #include #include #include #define SG_NEXT_CMD_LEN 0x2283 int main() { char buf[53] = { [36] = 0x7e, [52] = 0x02 }; int fd = open("/dev/sg1", O_RDWR); ioctl(fd, SG_NEXT_CMD_LEN, &(int){ 17 }); write(fd, buf, sizeof(buf)); } The crash was: BUG: unable to handle kernel paging request at ffff8cb97db37ffc IP: ata_bmdma_fill_sg drivers/ata/libata-sff.c:2623 [inline] IP: ata_bmdma_qc_prep+0xa4/0xc0 drivers/ata/libata-sff.c:2727 PGD fb6c067 P4D fb6c067 PUD 0 Oops: 0002 [#1] SMP CPU: 1 PID: 150 Comm: syz_ata_bmdma_q Not tainted 4.15.0-next-20180202 #99 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-20171110_100015-anatol 04/01/2014 [...] Call Trace: ata_qc_issue+0x100/0x1d0 drivers/ata/libata-core.c:5421 ata_scsi_translate+0xc9/0x1a0 drivers/ata/libata-scsi.c:2024 __ata_scsi_queuecmd drivers/ata/libata-scsi.c:4326 [inline] ata_scsi_queuecmd+0x8c/0x210 drivers/ata/libata-scsi.c:4375 scsi_dispatch_cmd+0xa2/0xe0 drivers/scsi/scsi_lib.c:1727 scsi_request_fn+0x24c/0x530 drivers/scsi/scsi_lib.c:1865 __blk_run_queue_uncond block/blk-core.c:412 [inline] __blk_run_queue+0x3a/0x60 block/blk-core.c:432 blk_execute_rq_nowait+0x93/0xc0 block/blk-exec.c:78 sg_common_write.isra.7+0x272/0x5a0 drivers/scsi/sg.c:806 sg_write+0x1ef/0x340 drivers/scsi/sg.c:677 __vfs_write+0x31/0x160 fs/read_write.c:480 vfs_write+0xa7/0x160 fs/read_write.c:544 SYSC_write fs/read_write.c:589 [inline] SyS_write+0x4d/0xc0 fs/read_write.c:581 do_syscall_64+0x5e/0x110 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x21/0x86 Fixes: 607126c2a21c ("libata-scsi: be tolerant of 12-byte ATAPI commands in 16-byte CDBs") Reported-by: syzbot+1ff6f9fcc3c35f1c72a95e26528c8e7e3276e4da@syzkaller.appspotmail.com Cc: # v2.6.24+ Signed-off-by: Eric Biggers Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman --- drivers/ata/libata-scsi.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/drivers/ata/libata-scsi.c +++ b/drivers/ata/libata-scsi.c @@ -4309,7 +4309,9 @@ static inline int __ata_scsi_queuecmd(st if (likely((scsi_op != ATA_16) || !atapi_passthru16)) { /* relay SCSI command to ATAPI device */ int len = COMMAND_SIZE(scsi_op); - if (unlikely(len > scmd->cmd_len || len > dev->cdb_len)) + if (unlikely(len > scmd->cmd_len || + len > dev->cdb_len || + scmd->cmd_len > ATAPI_CDB_LEN)) goto bad_cdb_len; xlat_func = atapi_xlat;