ghsa-xfr8-3rww-p6wv
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
fbdev: Fix do_register_framebuffer to prevent null-ptr-deref in fb_videomode_to_var
If fb_add_videomode() in do_register_framebuffer() fails to allocate memory for fb_videomode, it will later lead to a null-ptr dereference in fb_videomode_to_var(), as the fb_info is registered while not having the mode in modelist that is expected to be there, i.e. the one that is described in fb_info->var.
================================================================ general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] CPU: 1 PID: 30371 Comm: syz-executor.1 Not tainted 5.10.226-syzkaller #0 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 RIP: 0010:fb_videomode_to_var+0x24/0x610 drivers/video/fbdev/core/modedb.c:901 Call Trace: display_to_var+0x3a/0x7c0 drivers/video/fbdev/core/fbcon.c:929 fbcon_resize+0x3e2/0x8f0 drivers/video/fbdev/core/fbcon.c:2071 resize_screen drivers/tty/vt/vt.c:1176 [inline] vc_do_resize+0x53a/0x1170 drivers/tty/vt/vt.c:1263 fbcon_modechanged+0x3ac/0x6e0 drivers/video/fbdev/core/fbcon.c:2720 fbcon_update_vcs+0x43/0x60 drivers/video/fbdev/core/fbcon.c:2776 do_fb_ioctl+0x6d2/0x740 drivers/video/fbdev/core/fbmem.c:1128 fb_ioctl+0xe7/0x150 drivers/video/fbdev/core/fbmem.c:1203 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x19a/0x210 fs/ioctl.c:739 do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x67/0xd1 ================================================================
Even though fbcon_init() checks beforehand if fb_match_mode() in var_to_display() fails, it can not prevent the panic because fbcon_init() does not return error code. Considering this and the comment in the code about fb_match_mode() returning NULL - "This should not happen" - it is better to prevent registering the fb_info if its mode was not set successfully. Also move fb_add_videomode() closer to the beginning of do_register_framebuffer() to avoid having to do the cleanup on fail.
Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
{
"affected": [],
"aliases": [
"CVE-2025-38215"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-07-04T14:15:29Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nfbdev: Fix do_register_framebuffer to prevent null-ptr-deref in fb_videomode_to_var\n\nIf fb_add_videomode() in do_register_framebuffer() fails to allocate\nmemory for fb_videomode, it will later lead to a null-ptr dereference in\nfb_videomode_to_var(), as the fb_info is registered while not having the\nmode in modelist that is expected to be there, i.e. the one that is\ndescribed in fb_info-\u003evar.\n\n================================================================\ngeneral protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN NOPTI\nKASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]\nCPU: 1 PID: 30371 Comm: syz-executor.1 Not tainted 5.10.226-syzkaller #0\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014\nRIP: 0010:fb_videomode_to_var+0x24/0x610 drivers/video/fbdev/core/modedb.c:901\nCall Trace:\n display_to_var+0x3a/0x7c0 drivers/video/fbdev/core/fbcon.c:929\n fbcon_resize+0x3e2/0x8f0 drivers/video/fbdev/core/fbcon.c:2071\n resize_screen drivers/tty/vt/vt.c:1176 [inline]\n vc_do_resize+0x53a/0x1170 drivers/tty/vt/vt.c:1263\n fbcon_modechanged+0x3ac/0x6e0 drivers/video/fbdev/core/fbcon.c:2720\n fbcon_update_vcs+0x43/0x60 drivers/video/fbdev/core/fbcon.c:2776\n do_fb_ioctl+0x6d2/0x740 drivers/video/fbdev/core/fbmem.c:1128\n fb_ioctl+0xe7/0x150 drivers/video/fbdev/core/fbmem.c:1203\n vfs_ioctl fs/ioctl.c:48 [inline]\n __do_sys_ioctl fs/ioctl.c:753 [inline]\n __se_sys_ioctl fs/ioctl.c:739 [inline]\n __x64_sys_ioctl+0x19a/0x210 fs/ioctl.c:739\n do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46\n entry_SYSCALL_64_after_hwframe+0x67/0xd1\n================================================================\n\nEven though fbcon_init() checks beforehand if fb_match_mode() in\nvar_to_display() fails, it can not prevent the panic because fbcon_init()\ndoes not return error code. Considering this and the comment in the code\nabout fb_match_mode() returning NULL - \"This should not happen\" - it is\nbetter to prevent registering the fb_info if its mode was not set\nsuccessfully. Also move fb_add_videomode() closer to the beginning of\ndo_register_framebuffer() to avoid having to do the cleanup on fail.\n\nFound by Linux Verification Center (linuxtesting.org) with Syzkaller.",
"id": "GHSA-xfr8-3rww-p6wv",
"modified": "2025-07-06T12:30:25Z",
"published": "2025-07-04T15:31:09Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-38215"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0909b2b49c4546a7a08c80f53d93736b63270827"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/17186f1f90d34fa701e4f14e6818305151637b9e"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3f2098f4fba7718eb2501207ca6e99d22427f25a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/908c5bb64f9c4319902b8ca1aa3fef8f83302520"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d803c4c2a4ac8ce2be6d899d5c7ab0bf7ec355e9"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
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