Re: The disappearing sys_call_table export.

Christoph Hellwig
2003-05-08T19:04:54Z

On Thu, May 08, 2003 at 01:13:49PM -0500, Jesse Pollard wrote:
> Unless there is a LOCK on sys_call_table[SYS_fsync] another CPU could
> replace the pointer between lines 3 and 4. At that point line 4 would
> destroy the existing entry.. or destroy it when the original is restored,
> and would NOT be restoring the one insterted.

The the race in the replacement. The second race is in actually
using these hooks. As soon as you examine a user pointer/address
in there you're fundamentally racy vs. another thread manipulating
the user address space.