From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from picard.linux.it (picard.linux.it [213.254.12.146]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1A2A3C27C76 for ; Wed, 25 Jan 2023 21:39:14 +0000 (UTC) Received: from picard.linux.it (localhost [IPv6:::1]) by picard.linux.it (Postfix) with ESMTP id 41FD63CD3B1 for ; Wed, 25 Jan 2023 22:39:12 +0100 (CET) Received: from in-4.smtp.seeweb.it (in-4.smtp.seeweb.it [217.194.8.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-384)) (No client certificate requested) by picard.linux.it (Postfix) with ESMTPS id BF6C33C4D1C for ; Wed, 25 Jan 2023 22:39:02 +0100 (CET) Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by in-4.smtp.seeweb.it (Postfix) with ESMTPS id 3E9E1100042B for ; Wed, 25 Jan 2023 22:39:01 +0100 (CET) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 5B4C621D07; Wed, 25 Jan 2023 21:39:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1674682741; h=from:from:reply-to:reply-to:date:date:message-id:message-id:to:to: cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=jA5hj5UIK60tCsPYONBwWlR9qn/BddHKxXRhX3GAEyM=; b=HNNigFj0JnRZoAzEKI9ToIPSJGDiOOlEnLrEyNwr31IUPHh6836bJZfZJoIF9dGwnCJ0Ka P2WeLVGhN83X+k6+aBE+kYGK4E1snGw4T9Q2WOBTqWu667lN1rhPLZ3TW/9uv4gbKyljxG Uxl75JqvpjkjleiufBkpaKy3qyXLobU= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1674682741; h=from:from:reply-to:reply-to:date:date:message-id:message-id:to:to: cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=jA5hj5UIK60tCsPYONBwWlR9qn/BddHKxXRhX3GAEyM=; b=ynn+rRcvEMW5cFvElDvAKskNGR03OBdm+/qmeciCbTWAHOdvZLDItDCzmDVQmshKXYKgbi jZs0xyWuK+aA4JAQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id E85131358F; Wed, 25 Jan 2023 21:39:00 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 3eceMHSh0WPnIQAAMHmgww (envelope-from ); Wed, 25 Jan 2023 21:39:00 +0000 Date: Wed, 25 Jan 2023 22:38:58 +0100 From: Petr Vorel To: Richard Palethorpe Message-ID: References: <20230120135651.24816-1-rpalethorpe@suse.com> <87y1pxqltm.fsf@suse.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <87y1pxqltm.fsf@suse.de> X-Virus-Scanned: clamav-milter 0.102.4 at in-4.smtp.seeweb.it X-Virus-Status: Clean Subject: Re: [LTP] [PATCH] tst_assert: Fix buffer overflow in scanf X-BeenThere: ltp@lists.linux.it X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux Test Project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Petr Vorel Cc: ltp@lists.linux.it Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ltp-bounces+ltp=archiver.kernel.org@lists.linux.it Sender: "ltp" > Hello, > Cyril Hrubis writes: > > Hi! > >> The maximum field width of a string conversion does not include the > >> null byte. So we can overflow the buffer by one byte. > >> This can be triggered in ioctl_loop01 with -fsanitize=address even if > >> the file contents are far less than the buffer size: > >> tst_test.c:1558: TINFO: Timeout per run is 0h 00m 30s > >> tst_device.c:93: TINFO: Found free device 1 '/dev/loop1' > >> ioctl_loop01.c:85: TPASS: /sys/block/loop1/loop/partscan = 0 > >> ioctl_loop01.c:86: TPASS: /sys/block/loop1/loop/autoclear = 0 > >> ================================================================= > >> ==293==ERROR: AddressSanitizer: stack-buffer-overflow on address 0xf5c03420 at pc 0xf7952bf8 bp 0xff9cf9f8 sp 0xff9cf5d0 > >> WRITE of size 1025 at 0xf5c03420 thread T0 > >> #0 0xf7952bf7 (/lib/libasan.so.8+0x89bf7) (BuildId: f8d5331e88e5c1b8a8a55eda0a8e20503ea0d2b9) > >> #1 0xf7953879 in __isoc99_vfscanf (/lib/libasan.so.8+0x8a879) (BuildId: f8d5331e88e5c1b8a8a55eda0a8e20503ea0d2b9) > >> #2 0x8071f85 in safe_file_scanf /home/rich/qa/ltp/lib/safe_file_ops.c:139 > >> #3 0x80552ea in tst_assert_str /home/rich/qa/ltp/lib/tst_assert.c:60 > >> #4 0x804f17a in verify_ioctl_loop /home/rich/qa/ltp/testcases/kernel/syscalls/ioctl/ioctl_loop01.c:87 > >> #5 0x8061599 in run_tests /home/rich/qa/ltp/lib/tst_test.c:1380 > >> #6 0x8061599 in testrun /home/rich/qa/ltp/lib/tst_test.c:1463 > >> #7 0x8061599 in fork_testrun /home/rich/qa/ltp/lib/tst_test.c:1592 > >> #8 0x806877a in tst_run_tcases /home/rich/qa/ltp/lib/tst_test.c:1686 > >> #9 0x804e01b in main ../../../../include/tst_test.h:394 > >> #10 0xf7188294 in __libc_start_call_main (/lib/libc.so.6+0x23294) (BuildId: 87c7a50c8792985dd164f5af2d45b8e91d9f4391) > >> #11 0xf7188357 in __libc_start_main@@GLIBC_2.34 (/lib/libc.so.6+0x23357) (BuildId: 87c7a50c8792985dd164f5af2d45b8e91d9f4391) > >> #12 0x804e617 in _start ../sysdeps/i386/start.S:111 > >> Address 0xf5c03420 is located in stack of thread T0 at offset 1056 in frame > >> #0 0x805525f in tst_assert_str /home/rich/qa/ltp/lib/tst_assert.c:57 > >> This frame has 1 object(s): > >> [32, 1056) 'sys_val' (line 58) <== Memory access at offset 1056 overflows this variable > > Uff, looking closely at the scanf manual: > > String input conversions store a terminating null byte ('\0') to mark > > the end of the input; the maximum field width does not include this > > terminator. > > So do I get it right that scanf() actually writes one byte after the > > size passed after the % character? That sounds a bit evil to me. > Yes, I suppose the root cause is null terminated strings. ;-) Interesting. I dared to merge it (added your Signed-off-by:). Thanks! Kind regards, Petr > > Anyways: > > Reviewed-by: Cyril Hrubis > Thanks -- Mailing list info: https://lists.linux.it/listinfo/ltp