Author: asomers Date: Thu Jun 20 23:07:20 2019 New Revision: 349248 URL: https://svnweb.freebsd.org/changeset/base/349248
Log: 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 Modified: head/sys/fs/fifofs/fifo_vnops.c head/sys/kern/kern_descrip.c head/sys/kern/sys_pipe.c head/sys/kern/vfs_vnops.c head/sys/sys/file.h Modified: head/sys/fs/fifofs/fifo_vnops.c ============================================================================== --- head/sys/fs/fifofs/fifo_vnops.c Thu Jun 20 22:21:42 2019 (r349247) +++ head/sys/fs/fifofs/fifo_vnops.c Thu Jun 20 23:07:20 2019 (r349248) @@ -174,7 +174,7 @@ fifo_open(ap) if (fip->fi_writers > 0) wakeup(&fip->fi_writers); } - fp->f_seqcount = fpipe->pipe_wgen - fip->fi_writers; + fp->f_pipegen = fpipe->pipe_wgen - fip->fi_writers; } if (ap->a_mode & FWRITE) { if ((ap->a_mode & O_NONBLOCK) && fip->fi_readers == 0) { Modified: head/sys/kern/kern_descrip.c ============================================================================== --- head/sys/kern/kern_descrip.c Thu Jun 20 22:21:42 2019 (r349247) +++ head/sys/kern/kern_descrip.c Thu Jun 20 23:07:20 2019 (r349248) @@ -780,7 +780,9 @@ kern_fcntl(struct thread *td, int fd, int cmd, intptr_ } if (arg >= 0) { bsize = fp->f_vnode->v_mount->mnt_stat.f_iosize; - fp->f_seqcount = (arg + bsize - 1) / bsize; + arg = MIN(arg, INT_MAX - bsize + 1); + fp->f_seqcount = MIN(IO_SEQMAX, + (arg + bsize - 1) / bsize); atomic_set_int(&fp->f_flag, FRDAHEAD); } else { atomic_clear_int(&fp->f_flag, FRDAHEAD); Modified: head/sys/kern/sys_pipe.c ============================================================================== --- head/sys/kern/sys_pipe.c Thu Jun 20 22:21:42 2019 (r349247) +++ head/sys/kern/sys_pipe.c Thu Jun 20 23:07:20 2019 (r349248) @@ -1414,7 +1414,7 @@ pipe_poll(struct file *fp, int events, struct ucred *a levents = events & (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND); if (rpipe->pipe_state & PIPE_NAMED && fp->f_flag & FREAD && levents && - fp->f_seqcount == rpipe->pipe_wgen) + fp->f_pipegen == rpipe->pipe_wgen) events |= POLLINIGNEOF; if ((events & POLLINIGNEOF) == 0) { Modified: head/sys/kern/vfs_vnops.c ============================================================================== --- head/sys/kern/vfs_vnops.c Thu Jun 20 22:21:42 2019 (r349247) +++ head/sys/kern/vfs_vnops.c Thu Jun 20 23:07:20 2019 (r349248) @@ -499,7 +499,8 @@ sequential_heuristic(struct uio *uio, struct file *fp) * closely related to the best I/O size for real disks than * to any block size used by software. */ - fp->f_seqcount += howmany(uio->uio_resid, 16384); + fp->f_seqcount += MIN(IO_SEQMAX, + howmany(uio->uio_resid, 16384)); if (fp->f_seqcount > IO_SEQMAX) fp->f_seqcount = IO_SEQMAX; return (fp->f_seqcount << IO_SEQSHIFT); Modified: head/sys/sys/file.h ============================================================================== --- head/sys/sys/file.h Thu Jun 20 22:21:42 2019 (r349247) +++ head/sys/sys/file.h Thu Jun 20 23:07:20 2019 (r349248) @@ -179,7 +179,10 @@ struct file { /* * DTYPE_VNODE specific fields. */ - int f_seqcount; /* (a) Count of sequential accesses. */ + union { + int16_t f_seqcount; /* (a) Count of sequential accesses. */ + int f_pipegen; + }; off_t f_nextoff; /* next expected read/write offset. */ union { struct cdev_privdata *fvn_cdevpriv; _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
