================================================================== BUG: KASAN: vmalloc-out-of-bounds in fast_imageblit drivers/video/fbdev/core/sysimgblt.c:276 [inline] BUG: KASAN: vmalloc-out-of-bounds in sys_imageblit+0x1940/0x1d10 drivers/video/fbdev/core/sysimgblt.c:323 Write of size 4 at addr ffff800025769000 by task syz.3.309/6590 CPU: 0 PID: 6590 Comm: syz.3.309 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2026 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:276 [inline] sys_imageblit+0x1940/0x1d10 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+0x110c/0x18d0 drivers/video/fbdev/core/bitblit.c:409 fbcon_cursor+0x3c4/0x5a8 drivers/video/fbdev/core/fbcon.c:1342 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 do_output_char+0x4cc/0x7bc drivers/tty/n_tty.c:440 process_output drivers/tty/n_tty.c:506 [inline] n_tty_write+0xbec/0xf50 drivers/tty/n_tty.c:2389 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 call_write_iter include/linux/fs.h:2271 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x3c8/0x7c8 fs/read_write.c:584 ksys_write+0x12c/0x228 fs/read_write.c:637 __do_sys_write fs/read_write.c:649 [inline] __se_sys_write fs/read_write.c:646 [inline] __arm64_sys_write+0x7c/0x90 fs/read_write.c:646 __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+0x58/0x12c 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 0-page vmalloc region starting at 0xffff800025469000 allocated at drm_gem_shmem_vmap_locked drivers/gpu/drm/drm_gem_shmem_helper.c:320 [inline] The buggy address belongs to a 0-page vmalloc region starting at 0xffff800025469000 allocated at drm_gem_shmem_vmap+0x480/0x660 drivers/gpu/drm/drm_gem_shmem_helper.c:367 Memory state around the buggy address: ffff800025768f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff800025768f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff800025769000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ^ ffff800025769080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ffff800025769100: 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 ffff800025769000 KASAN: probably user-memory-access in range [0x000000012bb48000-0x000000012bb48007] 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=000000020bbcc000 [ffff800025769000] pgd=100000023ffff003, p4d=100000023ffff003, pud=100000023fffe003, pmd=100000010ebba003, pte=0000000000000000 Internal error: Oops: 0000000096000047 [#1] PREEMPT SMP Modules linked in: CPU: 0 PID: 6590 Comm: syz.3.309 Tainted: G B syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2026 pstate: 62400005 (nZCv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--) pc : fast_imageblit drivers/video/fbdev/core/sysimgblt.c:276 [inline] pc : sys_imageblit+0x1894/0x1d10 drivers/video/fbdev/core/sysimgblt.c:323 lr : fast_imageblit drivers/video/fbdev/core/sysimgblt.c:276 [inline] lr : sys_imageblit+0x1940/0x1d10 drivers/video/fbdev/core/sysimgblt.c:323 sp : ffff8000230572e0 x29: ffff800023057420 x28: 0000000000000001 x27: ffff800025769000 x26: ffff0000ce93cf1f x25: 0000000000000007 x24: 0000000000000008 x23: 0000000000000000 x22: ffff800025769000 x21: ffff8000230573a0 x20: 0000000000000000 x19: dfff800000000000 x18: 1fffe00033c1877e x17: ffff80001641d000 x16: ffff800011bcac18 x15: ffff00019e0c3bfc x14: 0000000000000001 x13: 1ffff00003203b6c x12: 0000000000080000 x11: 000000000007ffff x10: ffff800032797000 x9 : 0000000000000000 x8 : ffff0000cd4cd400 x7 : ffff800011d2c160 x6 : ffff80000825ab2c x5 : 0000000000000000 x4 : 0000000000000001 x3 : ffff800008195a30 x2 : 0000000000000001 x1 : 0000000000000000 x0 : 0000000000000001 Call trace: fast_imageblit drivers/video/fbdev/core/sysimgblt.c:276 [inline] sys_imageblit+0x1894/0x1d10 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+0x110c/0x18d0 drivers/video/fbdev/core/bitblit.c:409 fbcon_cursor+0x3c4/0x5a8 drivers/video/fbdev/core/fbcon.c:1342 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 do_output_char+0x4cc/0x7bc drivers/tty/n_tty.c:440 process_output drivers/tty/n_tty.c:506 [inline] n_tty_write+0xbec/0xf50 drivers/tty/n_tty.c:2389 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 call_write_iter include/linux/fs.h:2271 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x3c8/0x7c8 fs/read_write.c:584 ksys_write+0x12c/0x228 fs/read_write.c:637 __do_sys_write fs/read_write.c:649 [inline] __se_sys_write fs/read_write.c:646 [inline] __arm64_sys_write+0x7c/0x90 fs/read_write.c:646 __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+0x58/0x12c 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: b9400294 f2fbfff3 38ea6908 350004c8 (b80046d4) ---[ end trace 0000000000000000 ]--- ---------------- Code disassembly (best guess): 0: b9400294 ldr w20, [x20] 4: f2fbfff3 movk x19, #0xdfff, lsl #48 8: 38ea6908 ldrsb w8, [x8, x10] c: 350004c8 cbnz w8, 0xa4 * 10: b80046d4 str w20, [x22], #4 <-- trapping instruction