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pf: Don't hold PF_RULES_WLOCK during copyin() on DIOCRCLRTSTATS

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We cannot hold a non-sleepable lock during copyin(). This means we can't
safely count the table, so instead we fall back to the pf_ioctl_maxcount
used in other ioctls to protect against overly large requests.

Reported by:	syzbot+81e380344d4a6c37d78a@syzkaller.appspotmail.com
MFC after:	1 week
This commit is contained in:
Kristof Provost 2021-01-13 19:30:01 +01:00
parent fdaf9cb942
commit ea36212bf5
1 changed files with 8 additions and 9 deletions
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17
sys/netpfil/pf/pf_ioctl.c
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@ -3363,36 +3363,35 @@ pfioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags, struct thread *td
struct pfioc_table *io = (struct pfioc_table *)addr;
struct pfr_table *pfrts;
size_t totlen;
int n;
if (io->pfrio_esize != sizeof(struct pfr_table)) {
error = ENODEV;
break;
}
PF_RULES_WLOCK();
n = pfr_table_count(&io->pfrio_table, io->pfrio_flags);
if (n < 0) {
PF_RULES_WUNLOCK();
error = EINVAL;
if (io->pfrio_size < 0 || io->pfrio_size > pf_ioctl_maxcount ||
WOULD_OVERFLOW(io->pfrio_size, sizeof(struct pfr_table))) {
/* We used to count tables and use the minimum required
* size, so we didn't fail on overly large requests.
* Keep doing so. */
io->pfrio_size = pf_ioctl_maxcount;
break;
}
io->pfrio_size = min(io->pfrio_size, n);
totlen = io->pfrio_size * sizeof(struct pfr_table);
pfrts = mallocarray(io->pfrio_size, sizeof(struct pfr_table),
M_TEMP, M_NOWAIT);
if (pfrts == NULL) {
error = ENOMEM;
PF_RULES_WUNLOCK();
break;
}
error = copyin(io->pfrio_buffer, pfrts, totlen);
if (error) {
free(pfrts, M_TEMP);
PF_RULES_WUNLOCK();
break;
}
PF_RULES_WLOCK();
error = pfr_clr_tstats(pfrts, io->pfrio_size,
&io->pfrio_nzero, io->pfrio_flags | PFR_FLAG_USERIOCTL);
PF_RULES_WUNLOCK();