Author: asomers Date: Mon Aug 12 20:31:12 2019 New Revision: 350958 URL: https://svnweb.freebsd.org/changeset/base/350958
Log: MFC r349248, r349391, r350088 r349248: 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 Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D20710 r349391: fcntl: style changes to r349248 Reported by: bde MFC-With: 349248 Sponsored by: The FreeBSD Foundation r350088: F_READAHEAD: Fix r349248's overflow protection, broken by r349391 I accidentally broke the main point of r349248 when making stylistic changes in r349391. Restore the original behavior, and also fix an additional overflow that was possible when uio->uio_resid was nearly SSIZE_MAX. Reported by: cem Reviewed by: bde MFC-With: 349248 Sponsored by: The FreeBSD Foundation Modified: stable/12/sys/fs/fifofs/fifo_vnops.c stable/12/sys/kern/kern_descrip.c stable/12/sys/kern/sys_pipe.c stable/12/sys/kern/vfs_vnops.c stable/12/sys/sys/file.h Directory Properties: stable/12/ (props changed) Modified: stable/12/sys/fs/fifofs/fifo_vnops.c ============================================================================== --- stable/12/sys/fs/fifofs/fifo_vnops.c Mon Aug 12 20:27:33 2019 (r350957) +++ stable/12/sys/fs/fifofs/fifo_vnops.c Mon Aug 12 20:31:12 2019 (r350958) @@ -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: stable/12/sys/kern/kern_descrip.c ============================================================================== --- stable/12/sys/kern/kern_descrip.c Mon Aug 12 20:27:33 2019 (r350957) +++ stable/12/sys/kern/kern_descrip.c Mon Aug 12 20:31:12 2019 (r350958) @@ -781,7 +781,9 @@ 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: stable/12/sys/kern/sys_pipe.c ============================================================================== --- stable/12/sys/kern/sys_pipe.c Mon Aug 12 20:27:33 2019 (r350957) +++ stable/12/sys/kern/sys_pipe.c Mon Aug 12 20:31:12 2019 (r350958) @@ -1420,7 +1420,7 @@ 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: stable/12/sys/kern/vfs_vnops.c ============================================================================== --- stable/12/sys/kern/vfs_vnops.c Mon Aug 12 20:27:33 2019 (r350957) +++ stable/12/sys/kern/vfs_vnops.c Mon Aug 12 20:31:12 2019 (r350958) @@ -494,9 +494,13 @@ 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); - if (fp->f_seqcount > IO_SEQMAX) + if (uio->uio_resid >= IO_SEQMAX * 16384) fp->f_seqcount = IO_SEQMAX; + else { + fp->f_seqcount += howmany(uio->uio_resid, 16384); + if (fp->f_seqcount > IO_SEQMAX) + fp->f_seqcount = IO_SEQMAX; + } return (fp->f_seqcount << IO_SEQSHIFT); } Modified: stable/12/sys/sys/file.h ============================================================================== --- stable/12/sys/sys/file.h Mon Aug 12 20:27:33 2019 (r350957) +++ stable/12/sys/sys/file.h Mon Aug 12 20:31:12 2019 (r350958) @@ -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; _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "[email protected]"
