| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2022-48631: ext4: fix bug in extents parsing when eh_entries == 0 and eh_depth > 0 |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| ext4: fix bug in extents parsing when eh_entries == 0 and eh_depth > 0 |
| |
| When walking through an inode extents, the ext4_ext_binsearch_idx() function |
| assumes that the extent header has been previously validated. However, there |
| are no checks that verify that the number of entries (eh->eh_entries) is |
| non-zero when depth is > 0. And this will lead to problems because the |
| EXT_FIRST_INDEX() and EXT_LAST_INDEX() will return garbage and result in this: |
| |
| [ 135.245946] ------------[ cut here ]------------ |
| [ 135.247579] kernel BUG at fs/ext4/extents.c:2258! |
| [ 135.249045] invalid opcode: 0000 [#1] PREEMPT SMP |
| [ 135.250320] CPU: 2 PID: 238 Comm: tmp118 Not tainted 5.19.0-rc8+ #4 |
| [ 135.252067] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.15.0-0-g2dd4b9b-rebuilt.opensuse.org 04/01/2014 |
| [ 135.255065] RIP: 0010:ext4_ext_map_blocks+0xc20/0xcb0 |
| [ 135.256475] Code: |
| [ 135.261433] RSP: 0018:ffffc900005939f8 EFLAGS: 00010246 |
| [ 135.262847] RAX: 0000000000000024 RBX: ffffc90000593b70 RCX: 0000000000000023 |
| [ 135.264765] RDX: ffff8880038e5f10 RSI: 0000000000000003 RDI: ffff8880046e922c |
| [ 135.266670] RBP: ffff8880046e9348 R08: 0000000000000001 R09: ffff888002ca580c |
| [ 135.268576] R10: 0000000000002602 R11: 0000000000000000 R12: 0000000000000024 |
| [ 135.270477] R13: 0000000000000000 R14: 0000000000000024 R15: 0000000000000000 |
| [ 135.272394] FS: 00007fdabdc56740(0000) GS:ffff88807dd00000(0000) knlGS:0000000000000000 |
| [ 135.274510] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 |
| [ 135.276075] CR2: 00007ffc26bd4f00 CR3: 0000000006261004 CR4: 0000000000170ea0 |
| [ 135.277952] Call Trace: |
| [ 135.278635] <TASK> |
| [ 135.279247] ? preempt_count_add+0x6d/0xa0 |
| [ 135.280358] ? percpu_counter_add_batch+0x55/0xb0 |
| [ 135.281612] ? _raw_read_unlock+0x18/0x30 |
| [ 135.282704] ext4_map_blocks+0x294/0x5a0 |
| [ 135.283745] ? xa_load+0x6f/0xa0 |
| [ 135.284562] ext4_mpage_readpages+0x3d6/0x770 |
| [ 135.285646] read_pages+0x67/0x1d0 |
| [ 135.286492] ? folio_add_lru+0x51/0x80 |
| [ 135.287441] page_cache_ra_unbounded+0x124/0x170 |
| [ 135.288510] filemap_get_pages+0x23d/0x5a0 |
| [ 135.289457] ? path_openat+0xa72/0xdd0 |
| [ 135.290332] filemap_read+0xbf/0x300 |
| [ 135.291158] ? _raw_spin_lock_irqsave+0x17/0x40 |
| [ 135.292192] new_sync_read+0x103/0x170 |
| [ 135.293014] vfs_read+0x15d/0x180 |
| [ 135.293745] ksys_read+0xa1/0xe0 |
| [ 135.294461] do_syscall_64+0x3c/0x80 |
| [ 135.295284] entry_SYSCALL_64_after_hwframe+0x46/0xb0 |
| |
| This patch simply adds an extra check in __ext4_ext_check(), verifying that |
| eh_entries is not 0 when eh_depth is > 0. |
| |
| The Linux kernel CVE team has assigned CVE-2022-48631 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Fixed in 5.4.215 with commit bb7eb3ca4b3b0d2c7872cf1a41c30f5e5bd65df0 |
| Fixed in 5.10.146 with commit 958b0ee23f5ac106e7cc11472b71aa2ea9a033bc |
| Fixed in 5.15.71 with commit be4df018c0be5ebecf1ca510feacc23be415cefc |
| Fixed in 5.19.12 with commit 2f5e9de15e4f55fbf56f22d4a2ce406246cc462d |
| Fixed in 6.0 with commit 29a5b8a137ac8eb410cc823653a29ac0e7b7e1b0 |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2022-48631 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| fs/ext4/extents.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/bb7eb3ca4b3b0d2c7872cf1a41c30f5e5bd65df0 |
| https://git.kernel.org/stable/c/958b0ee23f5ac106e7cc11472b71aa2ea9a033bc |
| https://git.kernel.org/stable/c/be4df018c0be5ebecf1ca510feacc23be415cefc |
| https://git.kernel.org/stable/c/2f5e9de15e4f55fbf56f22d4a2ce406246cc462d |
| https://git.kernel.org/stable/c/29a5b8a137ac8eb410cc823653a29ac0e7b7e1b0 |
