CVE-2021-47126

In the Linux kernel, the following vulnerability has been resolved: ipv6:
Fix KASAN: slab-out-of-bounds Read in fib6_nh_flush_exceptions Reported by
syzbot: HEAD commit: 90c911ad Merge tag ‘fixes’ of
git://git.kernel.org/pub/scm… git tree:
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
dashboard link:
https://syzkaller.appspot.com/bug?extid=123aa35098fd3c000eb7 compiler:
Debian clang version 11.0.1-2
================================================================== BUG:
KASAN: slab-out-of-bounds in fib6_nh_get_excptn_bucket
net/ipv6/route.c:1604 [inline] BUG: KASAN: slab-out-of-bounds in
fib6_nh_flush_exceptions+0xbd/0x360 net/ipv6/route.c:1732 Read of size 8 at
addr ffff8880145c78f8 by task syz-executor.4/17760 CPU: 0 PID: 17760 Comm:
syz-executor.4 Not tainted 5.12.0-rc8-syzkaller #0 Call Trace: <IRQ>
__dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x202/0x31e
lib/dump_stack.c:120 print_address_description+0x5f/0x3b0
mm/kasan/report.c:232 __kasan_report mm/kasan/report.c:399 [inline]
kasan_report+0x15c/0x200 mm/kasan/report.c:416 fib6_nh_get_excptn_bucket
net/ipv6/route.c:1604 [inline] fib6_nh_flush_exceptions+0xbd/0x360
net/ipv6/route.c:1732 fib6_nh_release+0x9a/0x430 net/ipv6/route.c:3536
fib6_info_destroy_rcu+0xcb/0x1c0 net/ipv6/ip6_fib.c:174 rcu_do_batch
kernel/rcu/tree.c:2559 [inline] rcu_core+0x8f6/0x1450
kernel/rcu/tree.c:2794 __do_softirq+0x372/0x7a6 kernel/softirq.c:345
invoke_softirq kernel/softirq.c:221 [inline] __irq_exit_rcu+0x22c/0x260
kernel/softirq.c:422 irq_exit_rcu+0x5/0x20 kernel/softirq.c:434
sysvec_apic_timer_interrupt+0x91/0xb0 arch/x86/kernel/apic/apic.c:1100
</IRQ> asm_sysvec_apic_timer_interrupt+0x12/0x20
arch/x86/include/asm/idtentry.h:632 RIP: 0010:lock_acquire+0x1f6/0x720
kernel/locking/lockdep.c:5515 Code: f6 84 24 a1 00 00 00 02 0f 85 8d 02 00
00 f7 c3 00 02 00 00 49 bd 00 00 00 00 00 fc ff df 74 01 fb 48 c7 44 24 40
0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 4b c7 44 3d 09 00 00 00 00 43 c7
44 3d RSP: 0018:ffffc90009e06560 EFLAGS: 00000206 RAX: 1ffff920013c0cc0
RBX: 0000000000000246 RCX: dffffc0000000000 RDX: 0000000000000000 RSI:
0000000000000000 RDI: 0000000000000000 RBP: ffffc90009e066e0 R08:
dffffc0000000000 R09: fffffbfff1f992b1 R10: fffffbfff1f992b1 R11:
0000000000000000 R12: 0000000000000000 R13: dffffc0000000000 R14:
0000000000000000 R15: 1ffff920013c0cb4 rcu_lock_acquire+0x2a/0x30
include/linux/rcupdate.h:267 rcu_read_lock include/linux/rcupdate.h:656
[inline] ext4_get_group_info+0xea/0x340 fs/ext4/ext4.h:3231
ext4_mb_prefetch+0x123/0x5d0 fs/ext4/mballoc.c:2212
ext4_mb_regular_allocator+0x8a5/0x28f0 fs/ext4/mballoc.c:2379
ext4_mb_new_blocks+0xc6e/0x24f0 fs/ext4/mballoc.c:4982
ext4_ext_map_blocks+0x2be3/0x7210 fs/ext4/extents.c:4238
ext4_map_blocks+0xab3/0x1cb0 fs/ext4/inode.c:638 ext4_getblk+0x187/0x6c0
fs/ext4/inode.c:848 ext4_bread+0x2a/0x1c0 fs/ext4/inode.c:900
ext4_append+0x1a4/0x360 fs/ext4/namei.c:67 ext4_init_new_dir+0x337/0xa10
fs/ext4/namei.c:2768 ext4_mkdir+0x4b8/0xc00 fs/ext4/namei.c:2814
vfs_mkdir+0x45b/0x640 fs/namei.c:3819 ovl_do_mkdir
fs/overlayfs/overlayfs.h:161 [inline] ovl_mkdir_real+0x53/0x1a0
fs/overlayfs/dir.c:146 ovl_create_real+0x280/0x490 fs/overlayfs/dir.c:193
ovl_workdir_create+0x425/0x600 fs/overlayfs/super.c:788
ovl_make_workdir+0xed/0x1140 fs/overlayfs/super.c:1355 ovl_get_workdir
fs/overlayfs/super.c:1492 [inline] ovl_fill_super+0x39ee/0x5370
fs/overlayfs/super.c:2035 mount_nodev+0x52/0xe0 fs/super.c:1413
legacy_get_tree+0xea/0x180 fs/fs_context.c:592 vfs_get_tree+0x86/0x270
fs/super.c:1497 do_new_mount fs/namespace.c:2903 [inline]
path_mount+0x196f/0x2be0 fs/namespace.c:3233 do_mount fs/namespace.c:3246
[inline] __do_sys_mount fs/namespace.c:3454 [inline]
__se_sys_mount+0x2f9/0x3b0 fs/namespace.c:3431 do_syscall_64+0x2d/0x70
arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP:
0033:0x4665f9 Code: ff ff c3 66 2e 0f 1f 84 —truncated—