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[88.21.205.111]) by smtp.gmail.com with ESMTPSA id d2sm814662wrn.43.2020.12.01.11.10.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 01 Dec 2020 11:10:38 -0800 (PST) From: =?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= To: qemu-devel@nongnu.org Subject: [PATCH v2 2/4] hw/scsi/megasas: Assert cdb_len is valid in megasas_handle_scsi() Date: Tue, 1 Dec 2020 20:10:24 +0100 Message-Id: <20201201191026.4149955-3-philmd@redhat.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20201201191026.4149955-1-philmd@redhat.com> References: <20201201191026.4149955-1-philmd@redhat.com> MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=philmd@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=63.128.21.124; envelope-from=philmd@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -35 X-Spam_score: -3.6 X-Spam_bar: --- X-Spam_report: (-3.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.497, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Laurent Vivier , Fam Zheng , Thomas Huth , qemu-block@nongnu.org, Li Qiang , Hannes Reinecke , Alexander Bulekov , Paolo Bonzini , =?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= , Daniele Buono Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" cdb_len can not be zero... (or less than 6) here, else we have a out-of-bound read first in scsi_cdb_length(): 71 int scsi_cdb_length(uint8_t *buf) 72 { 73 int cdb_len; 74 75 switch (buf[0] >> 5) { 76 case 0: 77 cdb_len = 6; 78 break; Then another out-of-bound read when the size returned by scsi_cdb_length() is used. Figured out after reviewing: https://www.mail-archive.com/qemu-devel@nongnu.org/msg757937.html And reproduced fuzzing: qemu-fuzz-i386: hw/scsi/megasas.c:1679: int megasas_handle_scsi(MegasasState *, MegasasCmd *, int): Assertion `len > 0 && cdb_len >= len' failed. ==1689590== ERROR: libFuzzer: deadly signal #8 0x7f7a5d918e75 in __assert_fail (/lib64/libc.so.6+0x34e75) #9 0x55a1b95cf6d4 in megasas_handle_scsi hw/scsi/megasas.c:1679:5 #10 0x55a1b95cf6d4 in megasas_handle_frame hw/scsi/megasas.c:1975:24 #11 0x55a1b95cf6d4 in megasas_mmio_write hw/scsi/megasas.c:2132:9 #12 0x55a1b981972e in memory_region_write_accessor softmmu/memory.c:491:5 #13 0x55a1b981972e in access_with_adjusted_size softmmu/memory.c:552:18 #14 0x55a1b981972e in memory_region_dispatch_write softmmu/memory.c:1501:16 #15 0x55a1b97f0ab0 in flatview_write_continue softmmu/physmem.c:2759:23 #16 0x55a1b97ec3f2 in flatview_write softmmu/physmem.c:2799:14 #17 0x55a1b97ec3f2 in address_space_write softmmu/physmem.c:2891:18 #18 0x55a1b985c7cd in cpu_outw softmmu/ioport.c:70:5 #19 0x55a1b99577ac in qtest_process_command softmmu/qtest.c:481:13 Inspired-by: Daniele Buono Inspired-by: Alexander Bulekov Signed-off-by: Philippe Mathieu-Daudé --- hw/scsi/megasas.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/hw/scsi/megasas.c b/hw/scsi/megasas.c index 1a5fc5857db..f5ad4425b5b 100644 --- a/hw/scsi/megasas.c +++ b/hw/scsi/megasas.c @@ -1667,6 +1667,7 @@ static int megasas_handle_scsi(MegasasState *s, MegasasCmd *cmd, { uint8_t *cdb; int target_id, lun_id, cdb_len; + int len = -1; bool is_write; struct SCSIDevice *sdev = NULL; bool is_logical = (frame_cmd == MFI_CMD_LD_SCSI_IO); @@ -1676,6 +1677,10 @@ static int megasas_handle_scsi(MegasasState *s, MegasasCmd *cmd, lun_id = cmd->frame->header.lun_id; cdb_len = cmd->frame->header.cdb_len; + if (cdb_len > 0) { + len = scsi_cdb_length(cdb); + } + assert(len > 0 && cdb_len >= len); if (is_logical) { if (target_id >= MFI_MAX_LD || lun_id != 0) { trace_megasas_scsi_target_not_present(