freebsd-dev/sys/fs/fifofs
Alan Somers 38b06f8ac4 fcntl: fix overflow when setting F_READAHEAD
VOP_READ and VOP_WRITE take the seqcount in blocks in a 16-bit field.
However, fcntl allows you to set the seqcount in bytes to any nonnegative
31-bit value. The result can be a 16-bit overflow, which will be
sign-extended in functions like ffs_read. Fix this by sanitizing the
argument in kern_fcntl. As a matter of policy, limit to IO_SEQMAX rather
than INT16_MAX.

Also, fifos have overloaded the f_seqcount field for a completely different
purpose ever since r238936.  Formalize that by using a union type.

Reviewed by:	cem
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D20710
2019-06-20 23:07:20 +00:00
..
fifo_vnops.c fcntl: fix overflow when setting F_READAHEAD 2019-06-20 23:07:20 +00:00