Hello,
syzbot found the following issue on:
HEAD commit: 29ad81a1 arch/x86: add missing include to sparsemem.h git tree: https://github.com/google/kmsan.git master console output: https://syzkaller.appspot.com/x/log.txt?x=1001ac60d00000 kernel config: https://syzkaller.appspot.com/x/.config?x=c8e3b38ca92283e dashboard link: https://syzkaller.appspot.com/bug?extid=47fa9c9c648b765305b9 compiler: Debian clang version 11.0.1-2 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17ffe738d00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11ca2914d00000
IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+47fa9c9c648b765305b9@syzkaller.appspotmail.com
===================================================== BUG: KMSAN: kernel-infoleak in kmsan_copy_to_user+0x9c/0xb0 mm/kmsan/kmsan_hooks.c:249 CPU: 1 PID: 8225 Comm: syz-executor269 Not tainted 5.11.0-rc7-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x21c/0x280 lib/dump_stack.c:120 kmsan_report+0xfb/0x1e0 mm/kmsan/kmsan_report.c:118 kmsan_internal_check_memory+0x484/0x520 mm/kmsan/kmsan.c:437 kmsan_copy_to_user+0x9c/0xb0 mm/kmsan/kmsan_hooks.c:249 instrument_copy_to_user include/linux/instrumented.h:121 [inline] _copy_to_user+0x1ac/0x270 lib/usercopy.c:33 copy_to_user include/linux/uaccess.h:209 [inline] fb_cmap_to_user+0x40a/0x990 drivers/video/fbdev/core/fbcmap.c:208 do_fb_ioctl+0xc53/0x1090 drivers/video/fbdev/core/fbmem.c:1136 fb_ioctl+0x1e4/0x210 drivers/video/fbdev/core/fbmem.c:1185 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl+0x311/0x4d0 fs/ioctl.c:739 __x64_sys_ioctl+0x4a/0x70 fs/ioctl.c:739 do_syscall_64+0x9f/0x140 arch/x86/entry/common.c:48 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x43fbd9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 14 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffc68acbf98 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000400488 RCX: 000000000043fbd9 RDX: 0000000020007400 RSI: 0000000000004604 RDI: 0000000000000003 RBP: 0000000000000000 R08: 00007ffc68acc138 R09: 00007ffc68acc138 R10: 00007ffc68acba10 R11: 0000000000000246 R12: 0000000000403460 R13: 431bde82d7b634db R14: 00000000004ad018 R15: 0000000000400488
Uninit was created at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:121 [inline] kmsan_internal_poison_shadow+0x5c/0xf0 mm/kmsan/kmsan.c:104 kmsan_slab_alloc+0x8d/0xe0 mm/kmsan/kmsan_hooks.c:76 slab_alloc_node mm/slub.c:2907 [inline] slab_alloc mm/slub.c:2916 [inline] __kmalloc+0x378/0x560 mm/slub.c:3998 kmalloc include/linux/slab.h:557 [inline] fb_alloc_cmap_gfp+0x39b/0xa70 drivers/video/fbdev/core/fbcmap.c:104 fb_alloc_cmap+0x95/0xb0 drivers/video/fbdev/core/fbcmap.c:135 drm_fb_helper_alloc_fbi+0x106/0x3f0 drivers/gpu/drm/drm_fb_helper.c:563 drm_fb_helper_generic_probe+0x4f3/0xc70 drivers/gpu/drm/drm_fb_helper.c:2320 drm_fb_helper_single_fb_probe drivers/gpu/drm/drm_fb_helper.c:1658 [inline] __drm_fb_helper_initial_config_and_unlock+0x1cac/0x26c0 drivers/gpu/drm/drm_fb_helper.c:1816 drm_fb_helper_initial_config drivers/gpu/drm/drm_fb_helper.c:1911 [inline] drm_fbdev_client_hotplug+0xbb8/0xd70 drivers/gpu/drm/drm_fb_helper.c:2413 drm_fbdev_generic_setup+0x39d/0xa00 drivers/gpu/drm/drm_fb_helper.c:2495 vkms_init+0x880/0xa02 drivers/gpu/drm/vkms/vkms_drv.c:168 do_one_initcall+0x362/0x8d0 init/main.c:1226 do_initcall_level+0x1e7/0x35a init/main.c:1299 do_initcalls+0x127/0x1cb init/main.c:1315 do_basic_setup+0x33/0x36 init/main.c:1335 kernel_init_freeable+0x23d/0x390 init/main.c:1536 kernel_init+0x1f/0x840 init/main.c:1424 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
Bytes 0-1 of 2 are uninitialized Memory access of size 2 starts at ffff8881455651c0 Data copied to user address 0000000020007300 =====================================================
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