CVE-2022-49464

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

erofs: fix buffer copy overflow of ztailpacking feature

I got some KASAN report as below:

[ 46.959738] ================================================================== [ 46.960430] BUG: KASAN: use-after-free in zerofsshiftedtransform+0x2bd/0x370 [ 46.960430] Read of size 4074 at addr ffff8880300c2f8e by task fssum/188 ... [ 46.960430] Call Trace: [ 46.960430] <TASK> [ 46.960430] dumpstacklvl+0x41/0x5e [ 46.960430] printreport.cold+0xb2/0x6b7 [ 46.960430] ? zerofsshiftedtransform+0x2bd/0x370 [ 46.960430] kasanreport+0x8a/0x140 [ 46.960430] ? zerofsshiftedtransform+0x2bd/0x370 [ 46.960430] kasancheckrange+0x14d/0x1d0 [ 46.960430] memcpy+0x20/0x60 [ 46.960430] zerofsshiftedtransform+0x2bd/0x370 [ 46.960430] zerofsdecompress_pcluster+0xaae/0x1080

The root cause is that the tail pcluster won't be a complete filesystem block anymore. So if ztailpacking is used, the second part of an uncompressed tail pcluster may not be rq->pageofs_out.