| 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-2021-47191: scsi: scsi_debug: Fix out-of-bound read in resp_readcap16() |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| scsi: scsi_debug: Fix out-of-bound read in resp_readcap16() |
| |
| The following warning was observed running syzkaller: |
| |
| [ 3813.830724] sg_write: data in/out 65466/242 bytes for SCSI command 0x9e-- guessing data in; |
| [ 3813.830724] program syz-executor not setting count and/or reply_len properly |
| [ 3813.836956] ================================================================== |
| [ 3813.839465] BUG: KASAN: stack-out-of-bounds in sg_copy_buffer+0x157/0x1e0 |
| [ 3813.841773] Read of size 4096 at addr ffff8883cf80f540 by task syz-executor/1549 |
| [ 3813.846612] Call Trace: |
| [ 3813.846995] dump_stack+0x108/0x15f |
| [ 3813.847524] print_address_description+0xa5/0x372 |
| [ 3813.848243] kasan_report.cold+0x236/0x2a8 |
| [ 3813.849439] check_memory_region+0x240/0x270 |
| [ 3813.850094] memcpy+0x30/0x80 |
| [ 3813.850553] sg_copy_buffer+0x157/0x1e0 |
| [ 3813.853032] sg_copy_from_buffer+0x13/0x20 |
| [ 3813.853660] fill_from_dev_buffer+0x135/0x370 |
| [ 3813.854329] resp_readcap16+0x1ac/0x280 |
| [ 3813.856917] schedule_resp+0x41f/0x1630 |
| [ 3813.858203] scsi_debug_queuecommand+0xb32/0x17e0 |
| [ 3813.862699] scsi_dispatch_cmd+0x330/0x950 |
| [ 3813.863329] scsi_request_fn+0xd8e/0x1710 |
| [ 3813.863946] __blk_run_queue+0x10b/0x230 |
| [ 3813.864544] blk_execute_rq_nowait+0x1d8/0x400 |
| [ 3813.865220] sg_common_write.isra.0+0xe61/0x2420 |
| [ 3813.871637] sg_write+0x6c8/0xef0 |
| [ 3813.878853] __vfs_write+0xe4/0x800 |
| [ 3813.883487] vfs_write+0x17b/0x530 |
| [ 3813.884008] ksys_write+0x103/0x270 |
| [ 3813.886268] __x64_sys_write+0x77/0xc0 |
| [ 3813.886841] do_syscall_64+0x106/0x360 |
| [ 3813.887415] entry_SYSCALL_64_after_hwframe+0x44/0xa9 |
| |
| This issue can be reproduced with the following syzkaller log: |
| |
| r0 = openat(0xffffffffffffff9c, &(0x7f0000000040)='./file0\x00', 0x26e1, 0x0) |
| r1 = syz_open_procfs(0xffffffffffffffff, &(0x7f0000000000)='fd/3\x00') |
| open_by_handle_at(r1, &(0x7f00000003c0)=ANY=[@ANYRESHEX], 0x602000) |
| r2 = syz_open_dev$sg(&(0x7f0000000000), 0x0, 0x40782) |
| write$binfmt_aout(r2, &(0x7f0000000340)=ANY=[@ANYBLOB="00000000deff000000000000000000000000000000000000000000000000000047f007af9e107a41ec395f1bded7be24277a1501ff6196a83366f4e6362bc0ff2b247f68a972989b094b2da4fb3607fcf611a22dd04310d28c75039d"], 0x126) |
| |
| In resp_readcap16() we get "int alloc_len" value -1104926854, and then pass |
| the huge arr_len to fill_from_dev_buffer(), but arr is only 32 bytes. This |
| leads to OOB in sg_copy_buffer(). |
| |
| To solve this issue, define alloc_len as u32. |
| |
| The Linux kernel CVE team has assigned CVE-2021-47191 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Fixed in 5.10.82 with commit 3e20cb072679bdb47747ccc8bee3233a4cf0765a |
| Fixed in 5.15.5 with commit 5b8bed6464ad6653586e30df046185fd816ad999 |
| Fixed in 5.16 with commit 4e3ace0051e7e504b55d239daab8789dd89b863c |
| |
| 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-2021-47191 |
| 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: |
| drivers/scsi/scsi_debug.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/3e20cb072679bdb47747ccc8bee3233a4cf0765a |
| https://git.kernel.org/stable/c/5b8bed6464ad6653586e30df046185fd816ad999 |
| https://git.kernel.org/stable/c/4e3ace0051e7e504b55d239daab8789dd89b863c |
