CVE-2022-50546

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> ext4: fix uninititialized value in &amp;#39;ext4_evict_inode&amp;#39;<br /> <br /> Syzbot found the following issue:<br /> =====================================================<br /> BUG: KMSAN: uninit-value in ext4_evict_inode+0xdd/0x26b0 fs/ext4/inode.c:180<br /> ext4_evict_inode+0xdd/0x26b0 fs/ext4/inode.c:180<br /> evict+0x365/0x9a0 fs/inode.c:664<br /> iput_final fs/inode.c:1747 [inline]<br /> iput+0x985/0xdd0 fs/inode.c:1773<br /> __ext4_new_inode+0xe54/0x7ec0 fs/ext4/ialloc.c:1361<br /> ext4_mknod+0x376/0x840 fs/ext4/namei.c:2844<br /> vfs_mknod+0x79d/0x830 fs/namei.c:3914<br /> do_mknodat+0x47d/0xaa0<br /> __do_sys_mknodat fs/namei.c:3992 [inline]<br /> __se_sys_mknodat fs/namei.c:3989 [inline]<br /> __ia32_sys_mknodat+0xeb/0x150 fs/namei.c:3989<br /> do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]<br /> __do_fast_syscall_32+0xa2/0x100 arch/x86/entry/common.c:178<br /> do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203<br /> do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:246<br /> entry_SYSENTER_compat_after_hwframe+0x70/0x82<br /> <br /> Uninit was created at:<br /> __alloc_pages+0x9f1/0xe80 mm/page_alloc.c:5578<br /> alloc_pages+0xaae/0xd80 mm/mempolicy.c:2285<br /> alloc_slab_page mm/slub.c:1794 [inline]<br /> allocate_slab+0x1b5/0x1010 mm/slub.c:1939<br /> new_slab mm/slub.c:1992 [inline]<br /> ___slab_alloc+0x10c3/0x2d60 mm/slub.c:3180<br /> __slab_alloc mm/slub.c:3279 [inline]<br /> slab_alloc_node mm/slub.c:3364 [inline]<br /> slab_alloc mm/slub.c:3406 [inline]<br /> __kmem_cache_alloc_lru mm/slub.c:3413 [inline]<br /> kmem_cache_alloc_lru+0x6f3/0xb30 mm/slub.c:3429<br /> alloc_inode_sb include/linux/fs.h:3117 [inline]<br /> ext4_alloc_inode+0x5f/0x860 fs/ext4/super.c:1321<br /> alloc_inode+0x83/0x440 fs/inode.c:259<br /> new_inode_pseudo fs/inode.c:1018 [inline]<br /> new_inode+0x3b/0x430 fs/inode.c:1046<br /> __ext4_new_inode+0x2a7/0x7ec0 fs/ext4/ialloc.c:959<br /> ext4_mkdir+0x4d5/0x1560 fs/ext4/namei.c:2992<br /> vfs_mkdir+0x62a/0x870 fs/namei.c:4035<br /> do_mkdirat+0x466/0x7b0 fs/namei.c:4060<br /> __do_sys_mkdirat fs/namei.c:4075 [inline]<br /> __se_sys_mkdirat fs/namei.c:4073 [inline]<br /> __ia32_sys_mkdirat+0xc4/0x120 fs/namei.c:4073<br /> do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]<br /> __do_fast_syscall_32+0xa2/0x100 arch/x86/entry/common.c:178<br /> do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203<br /> do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:246<br /> entry_SYSENTER_compat_after_hwframe+0x70/0x82<br /> <br /> CPU: 1 PID: 4625 Comm: syz-executor.2 Not tainted 6.1.0-rc4-syzkaller-62821-gcb231e2f67ec #0<br /> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022<br /> =====================================================<br /> <br /> Now, &amp;#39;ext4_alloc_inode()&amp;#39; didn&amp;#39;t init &amp;#39;ei-&gt;i_flags&amp;#39;. If new inode failed<br /> before set &amp;#39;ei-&gt;i_flags&amp;#39; in &amp;#39;__ext4_new_inode()&amp;#39;, then do &amp;#39;iput()&amp;#39;. As after<br /> 6bc0d63dad7f commit will access &amp;#39;ei-&gt;i_flags&amp;#39; in &amp;#39;ext4_evict_inode()&amp;#39; which<br /> will lead to access uninit-value.<br /> To solve above issue just init &amp;#39;ei-&gt;i_flags&amp;#39; in &amp;#39;ext4_alloc_inode()&amp;#39;.