| 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-2021-47338: fbmem: Do not delete the mode that is still in use |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| fbmem: Do not delete the mode that is still in use |
| |
| The execution of fb_delete_videomode() is not based on the result of the |
| previous fbcon_mode_deleted(). As a result, the mode is directly deleted, |
| regardless of whether it is still in use, which may cause UAF. |
| |
| ================================================================== |
| BUG: KASAN: use-after-free in fb_mode_is_equal+0x36e/0x5e0 \ |
| drivers/video/fbdev/core/modedb.c:924 |
| Read of size 4 at addr ffff88807e0ddb1c by task syz-executor.0/18962 |
| |
| CPU: 2 PID: 18962 Comm: syz-executor.0 Not tainted 5.10.45-rc1+ #3 |
| Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ... |
| Call Trace: |
| __dump_stack lib/dump_stack.c:77 [inline] |
| dump_stack+0x137/0x1be lib/dump_stack.c:118 |
| print_address_description+0x6c/0x640 mm/kasan/report.c:385 |
| __kasan_report mm/kasan/report.c:545 [inline] |
| kasan_report+0x13d/0x1e0 mm/kasan/report.c:562 |
| fb_mode_is_equal+0x36e/0x5e0 drivers/video/fbdev/core/modedb.c:924 |
| fbcon_mode_deleted+0x16a/0x220 drivers/video/fbdev/core/fbcon.c:2746 |
| fb_set_var+0x1e1/0xdb0 drivers/video/fbdev/core/fbmem.c:975 |
| do_fb_ioctl+0x4d9/0x6e0 drivers/video/fbdev/core/fbmem.c:1108 |
| vfs_ioctl fs/ioctl.c:48 [inline] |
| __do_sys_ioctl fs/ioctl.c:753 [inline] |
| __se_sys_ioctl+0xfb/0x170 fs/ioctl.c:739 |
| do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 |
| entry_SYSCALL_64_after_hwframe+0x44/0xa9 |
| |
| Freed by task 18960: |
| kasan_save_stack mm/kasan/common.c:48 [inline] |
| kasan_set_track+0x3d/0x70 mm/kasan/common.c:56 |
| kasan_set_free_info+0x17/0x30 mm/kasan/generic.c:355 |
| __kasan_slab_free+0x108/0x140 mm/kasan/common.c:422 |
| slab_free_hook mm/slub.c:1541 [inline] |
| slab_free_freelist_hook+0xd6/0x1a0 mm/slub.c:1574 |
| slab_free mm/slub.c:3139 [inline] |
| kfree+0xca/0x3d0 mm/slub.c:4121 |
| fb_delete_videomode+0x56a/0x820 drivers/video/fbdev/core/modedb.c:1104 |
| fb_set_var+0x1f3/0xdb0 drivers/video/fbdev/core/fbmem.c:978 |
| do_fb_ioctl+0x4d9/0x6e0 drivers/video/fbdev/core/fbmem.c:1108 |
| vfs_ioctl fs/ioctl.c:48 [inline] |
| __do_sys_ioctl fs/ioctl.c:753 [inline] |
| __se_sys_ioctl+0xfb/0x170 fs/ioctl.c:739 |
| do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 |
| entry_SYSCALL_64_after_hwframe+0x44/0xa9 |
| |
| The Linux kernel CVE team has assigned CVE-2021-47338 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.3 with commit 13ff178ccd6d3b8074c542a911300b79c4eec255 and fixed in 5.4.134 with commit 359311b85ebec7c07c3a08ae2f3def946cad33fa |
| Issue introduced in 5.3 with commit 13ff178ccd6d3b8074c542a911300b79c4eec255 and fixed in 5.10.52 with commit 087bff9acd2ec6db3f61aceb3224bde90fe0f7f8 |
| Issue introduced in 5.3 with commit 13ff178ccd6d3b8074c542a911300b79c4eec255 and fixed in 5.12.19 with commit f193509afc7ff37a46862610c93b896044d5b693 |
| Issue introduced in 5.3 with commit 13ff178ccd6d3b8074c542a911300b79c4eec255 and fixed in 5.13.4 with commit d6e76469157d8f240e5dec6f8411aa8d306b1126 |
| Issue introduced in 5.3 with commit 13ff178ccd6d3b8074c542a911300b79c4eec255 and fixed in 5.14 with commit 0af778269a522c988ef0b4188556aba97fb420cc |
| |
| 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-2021-47338 |
| 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/video/fbdev/core/fbmem.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/359311b85ebec7c07c3a08ae2f3def946cad33fa |
| https://git.kernel.org/stable/c/087bff9acd2ec6db3f61aceb3224bde90fe0f7f8 |
| https://git.kernel.org/stable/c/f193509afc7ff37a46862610c93b896044d5b693 |
| https://git.kernel.org/stable/c/d6e76469157d8f240e5dec6f8411aa8d306b1126 |
| https://git.kernel.org/stable/c/0af778269a522c988ef0b4188556aba97fb420cc |
