| Message ID | 20210712085544.2828-1-thunder.leizhen@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/1] fbmem: Do not delete the mode that is still in use | expand |
On Mon, Jul 12, 2021 at 04:55:44PM +0800, Zhen Lei wrote: > 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 > > Fixes: 13ff178ccd6d ("fbcon: Call fbcon_mode_deleted/new_modelist directly") > Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> Nice catch, that indeed got lost. Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: <stable@vger.kernel.org> # v5.3+ Needs to be applied to drm-misc-fixes, but the tree isn't ready yet. -Daniel > --- > drivers/video/fbdev/core/fbmem.c | 12 +++++------- > 1 file changed, 5 insertions(+), 7 deletions(-) > > diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c > index 98f193078c05..1c855145711b 100644 > --- a/drivers/video/fbdev/core/fbmem.c > +++ b/drivers/video/fbdev/core/fbmem.c > @@ -970,13 +970,11 @@ fb_set_var(struct fb_info *info, struct fb_var_screeninfo *var) > fb_var_to_videomode(&mode2, &info->var); > /* make sure we don't delete the videomode of current var */ > ret = fb_mode_is_equal(&mode1, &mode2); > - > - if (!ret) > - fbcon_mode_deleted(info, &mode1); > - > - if (!ret) > - fb_delete_videomode(&mode1, &info->modelist); > - > + if (!ret) { > + ret = fbcon_mode_deleted(info, &mode1); > + if (!ret) > + fb_delete_videomode(&mode1, &info->modelist); > + } > > return ret ? -EINVAL : 0; > } > -- > 2.25.1 > >
On Mon, Jul 12, 2021 at 4:37 PM Daniel Vetter <daniel@ffwll.ch> wrote: > On Mon, Jul 12, 2021 at 04:55:44PM +0800, Zhen Lei wrote: > > 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 > > > > Fixes: 13ff178ccd6d ("fbcon: Call fbcon_mode_deleted/new_modelist directly") > > Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> > > Nice catch, that indeed got lost. > > Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> > Cc: <stable@vger.kernel.org> # v5.3+ > > Needs to be applied to drm-misc-fixes, but the tree isn't ready yet. Tree still isn't ready, adding Thomas. Thomas, can you pls apply this when drm-misc-fixes is forwarded? Thanks, Daniel > -Daniel > > > --- > > drivers/video/fbdev/core/fbmem.c | 12 +++++------- > > 1 file changed, 5 insertions(+), 7 deletions(-) > > > > diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c > > index 98f193078c05..1c855145711b 100644 > > --- a/drivers/video/fbdev/core/fbmem.c > > +++ b/drivers/video/fbdev/core/fbmem.c > > @@ -970,13 +970,11 @@ fb_set_var(struct fb_info *info, struct fb_var_screeninfo *var) > > fb_var_to_videomode(&mode2, &info->var); > > /* make sure we don't delete the videomode of current var */ > > ret = fb_mode_is_equal(&mode1, &mode2); > > - > > - if (!ret) > > - fbcon_mode_deleted(info, &mode1); > > - > > - if (!ret) > > - fb_delete_videomode(&mode1, &info->modelist); > > - > > + if (!ret) { > > + ret = fbcon_mode_deleted(info, &mode1); > > + if (!ret) > > + fb_delete_videomode(&mode1, &info->modelist); > > + } > > > > return ret ? -EINVAL : 0; > > } > > -- > > 2.25.1 > > > > > > -- > Daniel Vetter > Software Engineer, Intel Corporation > http://blog.ffwll.ch
diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index 98f193078c05..1c855145711b 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -970,13 +970,11 @@ fb_set_var(struct fb_info *info, struct fb_var_screeninfo *var) fb_var_to_videomode(&mode2, &info->var); /* make sure we don't delete the videomode of current var */ ret = fb_mode_is_equal(&mode1, &mode2); - - if (!ret) - fbcon_mode_deleted(info, &mode1); - - if (!ret) - fb_delete_videomode(&mode1, &info->modelist); - + if (!ret) { + ret = fbcon_mode_deleted(info, &mode1); + if (!ret) + fb_delete_videomode(&mode1, &info->modelist); + } return ret ? -EINVAL : 0; }
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 Fixes: 13ff178ccd6d ("fbcon: Call fbcon_mode_deleted/new_modelist directly") Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> --- drivers/video/fbdev/core/fbmem.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-)