Date: Tue, 29 Mar 2016 23:14:27 +0200 From: Yves-Alexis Perez <corsac@...ian.org> To: oss-security@...ts.openwall.com, Theodore Tso <tytso@...gle.com>, linux-ext4@...r.kernel.org Subject: Re: CVE Request - Linux kernel (multiple versions) ext2/ext3 filesystem DoS [dropping MITRE from CC since it's not about the CVE] [adding ext and Theodore to CC] On mar., 2016-03-29 at 19:24 +0200, Hugues ANGUELKOV wrote: > Hello, > > The linux kernel is prone to a Denial of service when mounting specially > crafted ext2/ext3 (possibly ext4) filesystems. This occurs in the function > ext4_handle_error who call the panic function on precise circumstance. Did you contact the upstream maintainers about this? I'm adding them just in case they're not already aware of that… > This was tested on severals linux kernel version: 3.10, 3.18, 3.19, on > real hardware and Xen DomU PV & HVM (the crash report attached is from a > Fedora 3.18 PV DomU), from different distribution release: Ubuntu, CentOS, > Fedora, Linux Mint, QubesOS. > This a low security impact bug, because generally only root can mount > image, however on Desktop (or possibly server?) system configured with > automount the bug is easily triggable (think of android smartphone?Haven't > test yet). > The crafted image may be burn onto SD card or USB key to crash a large > panel of linux box. > > > [ 929.200197] EXT4-fs error (device loop0): ext4_iget:4058: inode #2: comm > mount: bad extended attribute block 8390656 > [ 929.200226] Kernel panic - not syncing: EXT4-fs (device loop0): panic > forced after error > [ 929.200226] > [ 929.200230] CPU: 1 PID: 980 Comm: mount Tainted: G O > 3.18.17-8.pvops.qubes.x86_64 #1 > [ 929.200233] 0000000000000000 000000007533690c ffff88000ea07aa8 > ffffffff81722191 > [ 929.200237] 0000000000000000 ffffffff81a84108 ffff88000ea07b28 > ffffffff8171a462 > [ 929.200240] ffff880000000010 ffff88000ea07b38 ffff88000ea07ad8 > 000000007533690c > [ 929.200244] Call Trace: > [ 929.200249] [<ffffffff81722191>] dump_stack+0x46/0x58 > [ 929.200253] [<ffffffff8171a462>] panic+0xd0/0x204 > [ 929.200257] [<ffffffff812ae4d6>] ext4_handle_error.part.188+0x96/0xa0 > [ 929.200260] [<ffffffff812ae838>] __ext4_error_inode+0xa8/0x180 > [ 929.200264] [<ffffffff81292869>] ext4_iget+0x929/0xae0 > [ 929.200267] [<ffffffff812b31fb>] ext4_fill_super+0x18db/0x2b60 > [ 929.200270] [<ffffffff8120af20>] mount_bdev+0x1b0/0x1f0 > [ 929.200273] [<ffffffff812b1920>] ? ext4_calculate_overhead+0x3d0/0x3d0 > [ 929.200276] [<ffffffff812a3425>] ext4_mount+0x15/0x20 > [ 929.200278] [<ffffffff8120b879>] mount_fs+0x39/0x1b0 > [ 929.200282] [<ffffffff811afd95>] ? __alloc_percpu+0x15/0x20 > [ 929.200285] [<ffffffff8122754b>] vfs_kern_mount+0x6b/0x110 > [ 929.200287] [<ffffffff8122a38c>] do_mount+0x22c/0xb60 > [ 929.200290] [<ffffffff811aab96>] ? memdup_user+0x46/0x80 > [ 929.200292] [<ffffffff8122b002>] SyS_mount+0xa2/0x110 > [ 929.200295] [<ffffffff8172a609>] system_call_fastpath+0x12/0x17 > [ 929.200301] Kernel Offset: 0x0 from 0xffffffff81000000 (relocation > range: 0xffffffff80000000-0xffffffff9fffffff)c > > I cannot attach the PoC (2x2MB too large) nor sending it in plain text > (they are filesystems), so I've uploaded it on this website of free file > sharing ... (sorry for the inconvenient): > poc.ext2 https://1fichier.com/?zbk2gohk8s > poc.ext3 https://1fichier.com/?9r0c8agjfa > > Can you assign a CVE for this? > Thank for reading and your time. > > Hugues ANGUELKOV. > > -- Yves-Alexis Download attachment "signature.asc" of type "application/pgp-signature" (474 bytes)
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