From: Gaosheng Cui cuigaosheng1@huawei.com
[ Upstream commit 6fe888c4d2fb174408e4540bb2d5602b9f507f90 ]
Shifting signed 32-bit value by 31 bits is undefined, so changing significant bit to unsigned. The UBSAN warning calltrace like below:
UBSAN: shift-out-of-bounds in lib/fonts/fonts.c:139:20 left shift of 1 by 31 places cannot be represented in type 'int' <TASK> dump_stack_lvl+0x7d/0xa5 dump_stack+0x15/0x1b ubsan_epilogue+0xe/0x4e __ubsan_handle_shift_out_of_bounds+0x1e7/0x20c get_default_font+0x1c7/0x1f0 fbcon_startup+0x347/0x3a0 do_take_over_console+0xce/0x270 do_fbcon_takeover+0xa1/0x170 do_fb_registered+0x2a8/0x340 fbcon_fb_registered+0x47/0xe0 register_framebuffer+0x294/0x4a0 __drm_fb_helper_initial_config_and_unlock+0x43c/0x880 [drm_kms_helper] drm_fb_helper_initial_config+0x52/0x80 [drm_kms_helper] drm_fbdev_client_hotplug+0x156/0x1b0 [drm_kms_helper] drm_fbdev_generic_setup+0xfc/0x290 [drm_kms_helper] bochs_pci_probe+0x6ca/0x772 [bochs] local_pci_probe+0x4d/0xb0 pci_device_probe+0x119/0x320 really_probe+0x181/0x550 __driver_probe_device+0xc6/0x220 driver_probe_device+0x32/0x100 __driver_attach+0x195/0x200 bus_for_each_dev+0xbb/0x120 driver_attach+0x27/0x30 bus_add_driver+0x22e/0x2f0 driver_register+0xa9/0x190 __pci_register_driver+0x90/0xa0 bochs_pci_driver_init+0x52/0x1000 [bochs] do_one_initcall+0x76/0x430 do_init_module+0x61/0x28a load_module+0x1f82/0x2e50 __do_sys_finit_module+0xf8/0x190 __x64_sys_finit_module+0x23/0x30 do_syscall_64+0x58/0x80 entry_SYSCALL_64_after_hwframe+0x63/0xcd </TASK>
Link: https://lkml.kernel.org/r/20221031113829.4183153-1-cuigaosheng1@huawei.com Fixes: c81f717cb9e0 ("fbcon: Fix typo and bogus logic in get_default_font") Signed-off-by: Gaosheng Cui cuigaosheng1@huawei.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- lib/fonts/fonts.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/lib/fonts/fonts.c b/lib/fonts/fonts.c index 5f4b07b56cd9..973866438608 100644 --- a/lib/fonts/fonts.c +++ b/lib/fonts/fonts.c @@ -135,8 +135,8 @@ const struct font_desc *get_default_font(int xres, int yres, u32 font_w, if (res > 20) c += 20 - res;
- if ((font_w & (1 << (f->width - 1))) && - (font_h & (1 << (f->height - 1)))) + if ((font_w & (1U << (f->width - 1))) && + (font_h & (1U << (f->height - 1)))) c += 1000;
if (c > cc) {