================================================================== BUG: KASAN: vmalloc-out-of-bounds in fast_imageblit drivers/video/fbdev/core/sysimgblt.c:257 [inline] BUG: KASAN: vmalloc-out-of-bounds in sys_imageblit+0x1560/0x1d10 drivers/video/fbdev/core/sysimgblt.c:323 Write of size 4 at addr ffff8000248e9520 by task syz.8.703/7307 CPU: 1 PID: 7307 Comm: syz.8.703 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026 Call trace: dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:158 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165 __dump_stack+0x30/0x40 lib/dump_stack.c:88 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106 print_address_description+0x88/0x218 mm/kasan/report.c:316 print_report+0x50/0x68 mm/kasan/report.c:420 kasan_report+0xa8/0xfc mm/kasan/report.c:524 __asan_report_store4_noabort+0x2c/0x38 mm/kasan/report_generic.c:355 fast_imageblit drivers/video/fbdev/core/sysimgblt.c:257 [inline] sys_imageblit+0x1560/0x1d10 drivers/video/fbdev/core/sysimgblt.c:323 drm_fb_helper_sys_imageblit+0x40/0x464 drivers/gpu/drm/drm_fb_helper.c:864 drm_fbdev_fb_imageblit+0x170/0x1dc drivers/gpu/drm/drm_fb_helper.c:2402 soft_cursor+0x53c/0x6c4 drivers/video/fbdev/core/softcursor.c:74 bit_cursor+0x10cc/0x185c drivers/video/fbdev/core/bitblit.c:404 fbcon_cursor+0x3c4/0x5a8 drivers/video/fbdev/core/fbcon.c:1343 set_cursor drivers/tty/vt/vt.c:920 [inline] con_flush_chars+0x204/0x280 drivers/tty/vt/vt.c:3368 con_write+0x40/0x58 drivers/tty/vt/vt.c:3296 process_output_block drivers/tty/n_tty.c:586 [inline] n_tty_write+0xb60/0xf50 drivers/tty/n_tty.c:2377 do_tty_write drivers/tty/tty_io.c:1018 [inline] file_tty_write+0x3c0/0x6d8 drivers/tty/tty_io.c:1089 tty_write+0x44/0x54 drivers/tty/tty_io.c:1110 do_iter_readv_writev fs/read_write.c:-1 [inline] do_iter_write+0x520/0x93c fs/read_write.c:861 vfs_writev fs/read_write.c:934 [inline] do_writev+0x200/0x3d0 fs/read_write.c:977 __do_sys_writev fs/read_write.c:1050 [inline] __se_sys_writev fs/read_write.c:1047 [inline] __arm64_sys_writev+0x80/0x94 fs/read_write.c:1047 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 The buggy address belongs to a vmalloc virtual mapping Memory state around the buggy address: ffff8000248e9400: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ffff8000248e9480: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 >ffff8000248e9500: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ^ ffff8000248e9580: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ffff8000248e9600: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ================================================================== Unable to handle kernel paging request at virtual address ffff8000248e9520 KASAN: probably user-memory-access in range [0x000000012474a900-0x000000012474a907] Mem abort info: ESR = 0x0000000096000047 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x07: level 3 translation fault Data abort info: ISV = 0, ISS = 0x00000047 CM = 0, WnR = 1 swapper pgtable: 4k pages, 48-bit VAs, pgdp=000000020dd2e000 [ffff8000248e9520] pgd=100000023ffff003, p4d=100000023ffff003, pud=100000023fffe003, pmd=100000010c056003, pte=0000000000000000 Internal error: Oops: 0000000096000047 [#1] PREEMPT SMP Modules linked in: CPU: 1 PID: 7307 Comm: syz.8.703 Tainted: G B syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026 pstate: 82400005 (Nzcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--) pc : fast_imageblit drivers/video/fbdev/core/sysimgblt.c:257 [inline] pc : sys_imageblit+0x1338/0x1d10 drivers/video/fbdev/core/sysimgblt.c:323 lr : fast_imageblit drivers/video/fbdev/core/sysimgblt.c:257 [inline] lr : sys_imageblit+0x1560/0x1d10 drivers/video/fbdev/core/sysimgblt.c:323 sp : ffff800021d37220 x29: ffff800021d37360 x28: 0000000000000001 x27: ffff8000248e9520 x26: ffff0000ce685c81 x25: 1fffe00019cd0b90 x24: ffff8000248e9520 x23: ffff8000248e9520 x22: 0000000000000000 x21: ffff800021d372e0 x20: 0000000000000000 x19: ffff0000ce685c80 x18: 1fffe00033e7697e x17: ffff80001537d000 x16: ffff800011b90080 x15: ffff00019f3b4bfc x14: 0000000000000001 x13: 1ffff00002ff016c x12: 0000000000080000 x11: dfff800000000000 x10: ffff800038651000 x9 : 0000000000000000 x8 : ffff0000d0128000 x7 : ffff800011cec160 x6 : ffff80000825ab50 x5 : 0000000000000000 x4 : 0000000000000001 x3 : ffff800008195a38 x2 : 0000000000000001 x1 : 0000000000000000 x0 : ffff8000248e9520 Call trace: fast_imageblit drivers/video/fbdev/core/sysimgblt.c:257 [inline] sys_imageblit+0x1338/0x1d10 drivers/video/fbdev/core/sysimgblt.c:323 drm_fb_helper_sys_imageblit+0x40/0x464 drivers/gpu/drm/drm_fb_helper.c:864 drm_fbdev_fb_imageblit+0x170/0x1dc drivers/gpu/drm/drm_fb_helper.c:2402 soft_cursor+0x53c/0x6c4 drivers/video/fbdev/core/softcursor.c:74 bit_cursor+0x10cc/0x185c drivers/video/fbdev/core/bitblit.c:404 fbcon_cursor+0x3c4/0x5a8 drivers/video/fbdev/core/fbcon.c:1343 set_cursor drivers/tty/vt/vt.c:920 [inline] con_flush_chars+0x204/0x280 drivers/tty/vt/vt.c:3368 con_write+0x40/0x58 drivers/tty/vt/vt.c:3296 process_output_block drivers/tty/n_tty.c:586 [inline] n_tty_write+0xb60/0xf50 drivers/tty/n_tty.c:2377 do_tty_write drivers/tty/tty_io.c:1018 [inline] file_tty_write+0x3c0/0x6d8 drivers/tty/tty_io.c:1089 tty_write+0x44/0x54 drivers/tty/tty_io.c:1110 do_iter_readv_writev fs/read_write.c:-1 [inline] do_iter_write+0x520/0x93c fs/read_write.c:861 vfs_writev fs/read_write.c:934 [inline] do_writev+0x200/0x3d0 fs/read_write.c:977 __do_sys_writev fs/read_write.c:1050 [inline] __se_sys_writev fs/read_write.c:1047 [inline] __arm64_sys_writev+0x80/0x94 fs/read_write.c:1047 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 Code: 38eb6928 b86a5ab4 350010c8 8b160360 (b8004414) ---[ end trace 0000000000000000 ]--- ---------------- Code disassembly (best guess): 0: 38eb6928 ldrsb w8, [x9, x11] 4: b86a5ab4 ldr w20, [x21, w10, uxtw #2] 8: 350010c8 cbnz w8, 0x220 c: 8b160360 add x0, x27, x22 * 10: b8004414 str w20, [x0], #4 <-- trapping instruction