On Mon, Oct 31, 2022 at 10:26:21PM +0800, Gaosheng Cui wrote:
> Shifting signed 32-bit value by 31 bits is undefined, so changing most
> significant bit to unsigned, and mark all of the flags as unsigned so
> that we don't mix types. The UBSAN warning calltrace like below:
>
> UBSAN: shift-out-of-bounds in fs/namespace.c:2330:33
> left shift of 1 by 31 places cannot be represented in type 'int'
> Call Trace:
> <TASK>
> dump_stack_lvl+0x7d/0xa5
> dump_stack+0x15/0x1b
> ubsan_epilogue+0xe/0x4e
> __ubsan_handle_shift_out_of_bounds+0x1e7/0x20c
> graft_tree+0x36/0xf0
> do_add_mount+0x98/0x100
> path_mount+0xbd6/0xd50
> init_mount+0x6a/0xa3
> devtmpfs_setup+0x47/0x7e
> devtmpfsd+0x1a/0x50
> kthread+0x126/0x160
> ret_from_fork+0x1f/0x30
> </TASK>
>
> Fixes: e462ec50cb5f ("VFS: Differentiate mount flags (MS_*) from internal superblock flags")
> Signed-off-by: Gaosheng Cui <cuigaosheng1@xxxxxxxxxx>
Reviewed-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
