CVE-2021-47637

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> ubifs: Fix deadlock in concurrent rename whiteout and inode writeback<br /> <br /> Following hung tasks:<br /> [ 77.028764] task:kworker/u8:4 state:D stack: 0 pid: 132<br /> [ 77.028820] Call Trace:<br /> [ 77.029027] schedule+0x8c/0x1b0<br /> [ 77.029067] mutex_lock+0x50/0x60<br /> [ 77.029074] ubifs_write_inode+0x68/0x1f0 [ubifs]<br /> [ 77.029117] __writeback_single_inode+0x43c/0x570<br /> [ 77.029128] writeback_sb_inodes+0x259/0x740<br /> [ 77.029148] wb_writeback+0x107/0x4d0<br /> [ 77.029163] wb_workfn+0x162/0x7b0<br /> <br /> [ 92.390442] task:aa state:D stack: 0 pid: 1506<br /> [ 92.390448] Call Trace:<br /> [ 92.390458] schedule+0x8c/0x1b0<br /> [ 92.390461] wb_wait_for_completion+0x82/0xd0<br /> [ 92.390469] __writeback_inodes_sb_nr+0xb2/0x110<br /> [ 92.390472] writeback_inodes_sb_nr+0x14/0x20<br /> [ 92.390476] ubifs_budget_space+0x705/0xdd0 [ubifs]<br /> [ 92.390503] do_rename.cold+0x7f/0x187 [ubifs]<br /> [ 92.390549] ubifs_rename+0x8b/0x180 [ubifs]<br /> [ 92.390571] vfs_rename+0xdb2/0x1170<br /> [ 92.390580] do_renameat2+0x554/0x770<br /> <br /> , are caused by concurrent rename whiteout and inode writeback processes:<br /> rename_whiteout(Thread 1) wb_workfn(Thread2)<br /> ubifs_rename<br /> do_rename<br /> lock_4_inodes (Hold ui_mutex)<br /> ubifs_budget_space<br /> make_free_space<br /> shrink_liability<br /> __writeback_inodes_sb_nr<br /> bdi_split_work_to_wbs (Queue new wb work)<br /> wb_do_writeback(wb work)<br /> __writeback_single_inode<br /> ubifs_write_inode<br /> LOCK(ui_mutex)<br /> ↑<br /> wb_wait_for_completion (Wait wb work)