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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) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1606849845; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=IjqfFE4wAjPA6W+4g0HRWJuF/SKb/AgR1wTwW244iqE=; b=TQJZENeEFUM3TywJllH3/np3r1gfOOTaJ0CagLXAHTPOAhZ4gPCTsZ65vmr9OhnHBszbcm K8RWCbkp+BKQR4lYcKlrIsIeeQaIh+F0Dms/QiCHGq1oaSWfupzctwpwwCRDAETPhSMK+I TGLhKIiTwn8P/bZ3izk+0Udjew6bXOk= X-MC-Unique: NM4TmUv3PHWfzr17qiVU2A-1 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=IjqfFE4wAjPA6W+4g0HRWJuF/SKb/AgR1wTwW244iqE=; b=cbgb4DokRawT0fkDsUiphyj1nfkOivLDt7/E969aU4j6oZTCJIPF5Rz+0tiNieR8tC OhHTHEsMZTZ4fgPrHYqlwk3p70OLRqcB9t0HXijJ3LdDcRMRZBY7MvADk/g+vmeYYDHa JL/bBJDmDMcsWPriXc5rZF4f9fnM0eCPKcpORmOsFl/55zmLvYQ1JpW36ifc1CUDBPId JIotlE7r3qX/f4k8E905xvIB3pLplzhdCWo1QniVazjjB1ImQvGKwKNbpYStGTxIM3i0 j/8zYKguob8x/qDfPwOFUHTnGcgxR8OTbYCOpzonmFdmKCStpBWyxNGKZKfAgTR4u+wA pFeQ== X-Gm-Message-State: AOAM532s8GmQd+mawM68D1iWDtJNzPN7b7xBdIAzPxMuk9Lz7TH414Gr duCSfeL+y3xQWH73FsjA25JhBNcxevyGVebFPPBlsq+MZ5z480neSTOh063sOMFGhkADTiymUfP wOo7vjgaa9tBzJg== X-Received: by 2002:a7b:cd90:: with SMTP id y16mr4219497wmj.115.1606849839324; Tue, 01 Dec 2020 11:10:39 -0800 (PST) X-Google-Smtp-Source: ABdhPJwYV+xBkY4QniZVOYMWFPWaKiS9tJyJbhljO0KUVTIejeKa9QDyJkFA4gfoElhZ5XaWqqJ4ew== X-Received: by 2002:a7b:cd90:: with SMTP id y16mr4219481wmj.115.1606849839168; Tue, 01 Dec 2020 11:10:39 -0800 (PST) From: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= To: qemu-devel@nongnu.org Cc: Laurent Vivier , Thomas Huth , Hannes Reinecke , Fam Zheng , Li Qiang , Alexander Bulekov , qemu-block@nongnu.org, Paolo Bonzini , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Daniele Buono 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 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @redhat.com) 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 =3D 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(MegasasSt= ate *, MegasasCmd *, int): Assertion `len > 0 && cdb_len >=3D len' failed. =3D=3D1689590=3D=3D 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:4= 91:5 #13 0x55a1b981972e in access_with_adjusted_size softmmu/memory.c:552:= 18 #14 0x55a1b981972e in memory_region_dispatch_write softmmu/memory.c:1= 501:16 #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-Daud=C3=A9 --- 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, Megas= asCmd *cmd, { uint8_t *cdb; int target_id, lun_id, cdb_len; + int len =3D -1; bool is_write; struct SCSIDevice *sdev =3D NULL; bool is_logical =3D (frame_cmd =3D=3D MFI_CMD_LD_SCSI_IO); @@ -1676,6 +1677,10 @@ static int megasas_handle_scsi(MegasasState *s, Mega= sasCmd *cmd, lun_id =3D cmd->frame->header.lun_id; cdb_len =3D cmd->frame->header.cdb_len; =20 + if (cdb_len > 0) { + len =3D scsi_cdb_length(cdb); + } + assert(len > 0 && cdb_len >=3D len); if (is_logical) { if (target_id >=3D MFI_MAX_LD || lun_id !=3D 0) { trace_megasas_scsi_target_not_present( --=20 2.26.2