| 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-2021-47636: ubifs: Fix read out-of-bounds in ubifs_wbuf_write_nolock() |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| ubifs: Fix read out-of-bounds in ubifs_wbuf_write_nolock() |
| |
| Function ubifs_wbuf_write_nolock() may access buf out of bounds in |
| following process: |
| |
| ubifs_wbuf_write_nolock(): |
| aligned_len = ALIGN(len, 8); // Assume len = 4089, aligned_len = 4096 |
| if (aligned_len <= wbuf->avail) ... // Not satisfy |
| if (wbuf->used) { |
| ubifs_leb_write() // Fill some data in avail wbuf |
| len -= wbuf->avail; // len is still not 8-bytes aligned |
| aligned_len -= wbuf->avail; |
| } |
| n = aligned_len >> c->max_write_shift; |
| if (n) { |
| n <<= c->max_write_shift; |
| err = ubifs_leb_write(c, wbuf->lnum, buf + written, |
| wbuf->offs, n); |
| // n > len, read out of bounds less than 8(n-len) bytes |
| } |
| |
| , which can be catched by KASAN: |
| ========================================================= |
| BUG: KASAN: slab-out-of-bounds in ecc_sw_hamming_calculate+0x1dc/0x7d0 |
| Read of size 4 at addr ffff888105594ff8 by task kworker/u8:4/128 |
| Workqueue: writeback wb_workfn (flush-ubifs_0_0) |
| Call Trace: |
| kasan_report.cold+0x81/0x165 |
| nand_write_page_swecc+0xa9/0x160 |
| ubifs_leb_write+0xf2/0x1b0 [ubifs] |
| ubifs_wbuf_write_nolock+0x421/0x12c0 [ubifs] |
| write_head+0xdc/0x1c0 [ubifs] |
| ubifs_jnl_write_inode+0x627/0x960 [ubifs] |
| wb_workfn+0x8af/0xb80 |
| |
| Function ubifs_wbuf_write_nolock() accepts that parameter 'len' is not 8 |
| bytes aligned, the 'len' represents the true length of buf (which is |
| allocated in 'ubifs_jnl_xxx', eg. ubifs_jnl_write_inode), so |
| ubifs_wbuf_write_nolock() must handle the length read from 'buf' carefully |
| to write leb safely. |
| |
| Fetch a reproducer in [Link]. |
| |
| The Linux kernel CVE team has assigned CVE-2021-47636 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 2.6.27 with commit 1e51764a3c2ac05a23a22b2a95ddee4d9bffb16d and fixed in 4.19.238 with commit 5343575aa11c5d7044107d59d43f84aec01312b0 |
| Issue introduced in 2.6.27 with commit 1e51764a3c2ac05a23a22b2a95ddee4d9bffb16d and fixed in 5.4.189 with commit b80ccbec0e4804436c382d7dd60e943c386ed83a |
| Issue introduced in 2.6.27 with commit 1e51764a3c2ac05a23a22b2a95ddee4d9bffb16d and fixed in 5.10.110 with commit 07a209fadee7b53b46858538e1177597273862e4 |
| Issue introduced in 2.6.27 with commit 1e51764a3c2ac05a23a22b2a95ddee4d9bffb16d and fixed in 5.15.33 with commit a7054aaf1909cf40489c0ec1b728fdcf79c751a6 |
| Issue introduced in 2.6.27 with commit 1e51764a3c2ac05a23a22b2a95ddee4d9bffb16d and fixed in 5.16.19 with commit e09fa5318d51f522e1af4fbaf8f74999355980c8 |
| Issue introduced in 2.6.27 with commit 1e51764a3c2ac05a23a22b2a95ddee4d9bffb16d and fixed in 5.17.2 with commit 3b7fb89135a20587d57f8877c02e25003e9edbdf |
| Issue introduced in 2.6.27 with commit 1e51764a3c2ac05a23a22b2a95ddee4d9bffb16d and fixed in 5.18 with commit 4f2262a334641e05f645364d5ade1f565c85f20b |
| |
| 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-2021-47636 |
| 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/ubifs/io.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/5343575aa11c5d7044107d59d43f84aec01312b0 |
| https://git.kernel.org/stable/c/b80ccbec0e4804436c382d7dd60e943c386ed83a |
| https://git.kernel.org/stable/c/07a209fadee7b53b46858538e1177597273862e4 |
| https://git.kernel.org/stable/c/a7054aaf1909cf40489c0ec1b728fdcf79c751a6 |
| https://git.kernel.org/stable/c/e09fa5318d51f522e1af4fbaf8f74999355980c8 |
| https://git.kernel.org/stable/c/3b7fb89135a20587d57f8877c02e25003e9edbdf |
| https://git.kernel.org/stable/c/4f2262a334641e05f645364d5ade1f565c85f20b |
