In the Linux kernel, the following vulnerability has been resolved:

ext4: fix uninititialized value in 'ext4evictinode'

Syzbot found the following issue:

BUG: KMSAN: uninit-value in ext4evictinode+0xdd/0x26b0 fs/ext4/inode.c:180 ext4evictinode+0xdd/0x26b0 fs/ext4/inode.c:180 evict+0x365/0x9a0 fs/inode.c:664 iput_final fs/inode.c:1747 [inline] iput+0x985/0xdd0 fs/inode.c:1773 __ext4newinode+0xe54/0x7ec0 fs/ext4/ialloc.c:1361 ext4mknod+0x376/0x840 fs/ext4/namei.c:2844 vfsmknod+0x79d/0x830 fs/namei.c:3914 do_mknodat+0x47d/0xaa0 __dosysmknodat fs/namei.c:3992 [inline] __sesysmknodat fs/namei.c:3989 [inline] __ia32sysmknodat+0xeb/0x150 fs/namei.c:3989 dosyscall32irqson arch/x86/entry/common.c:112 [inline] __dofastsyscall32+0xa2/0x100 arch/x86/entry/common.c:178 dofastsyscall32+0x33/0x70 arch/x86/entry/common.c:203 doSYSENTER32+0x1b/0x20 arch/x86/entry/common.c:246 entrySYSENTERcompatafterhwframe+0x70/0x82

Uninit was created at: __allocpages+0x9f1/0xe80 mm/pagealloc.c:5578 alloc_pages+0xaae/0xd80 mm/mempolicy.c:2285 allocslabpage mm/slub.c:1794 [inline] allocateslab+0x1b5/0x1010 mm/slub.c:1939 newslab mm/slub.c:1992 [inline] ___slab_alloc+0x10c3/0x2d60 mm/slub.c:3180 __slaballoc mm/slub.c:3279 [inline] slaballocnode mm/slub.c:3364 [inline] slaballoc mm/slub.c:3406 [inline] __kmemcachealloclru mm/slub.c:3413 [inline] kmemcachealloclru+0x6f3/0xb30 mm/slub.c:3429 allocinodesb include/linux/fs.h:3117 [inline] ext4allocinode+0x5f/0x860 fs/ext4/super.c:1321 allocinode+0x83/0x440 fs/inode.c:259 newinodepseudo fs/inode.c:1018 [inline] newinode+0x3b/0x430 fs/inode.c:1046 __ext4newinode+0x2a7/0x7ec0 fs/ext4/ialloc.c:959 ext4_mkdir+0x4d5/0x1560 fs/ext4/namei.c:2992 vfsmkdir+0x62a/0x870 fs/namei.c:4035 domkdirat+0x466/0x7b0 fs/namei.c:4060 __dosysmkdirat fs/namei.c:4075 [inline] __sesysmkdirat fs/namei.c:4073 [inline] __ia32sysmkdirat+0xc4/0x120 fs/namei.c:4073 dosyscall32irqson arch/x86/entry/common.c:112 [inline] __dofastsyscall32+0xa2/0x100 arch/x86/entry/common.c:178 dofastsyscall32+0x33/0x70 arch/x86/entry/common.c:203 doSYSENTER32+0x1b/0x20 arch/x86/entry/common.c:246 entrySYSENTERcompatafterhwframe+0x70/0x82

CPU: 1 PID: 4625 Comm: syz-executor.2 Not tainted 6.1.0-rc4-syzkaller-62821-gcb231e2f67ec #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022

Now, 'ext4allocinode()' didn't init 'ei->iflags'. If new inode failed before set 'ei->iflags' in '__ext4newinode()', then do 'iput()'. As after 6bc0d63dad7f commit will access 'ei->iflags' in 'ext4evictinode()' which will lead to access uninit-value. To solve above issue just init 'ei->iflags' in 'ext4allocinode()'.