d/freebsd-nq
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Set pca.p_bufr to NULL when we haven't allocated a buffer.

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Otherwise, p_bufr is set to garbage on the stack, and if that garbage
happens to be non-NULL, and the TOLOG or TOCONS flag is set, putbuf()
will get called and attempt to fill the non-existent buffer.

This is really only relevant for tprintf() (and only when the priority is
not -1), but set it in uprintf() and ttyprintf() for completeness.

The next step, to avoid log buffer scrambling, would be to add the
PRINTF_BUFR_SIZE code to tprintf(), but this should prevent panics.

Submitted by:	rmacklem
Found by:	pho
This commit is contained in:
Kenneth D. Merry 2011-06-07 05:04:37 +00:00
parent 1d90532abe
commit 5e319c480c
1 changed files with 3 additions and 0 deletions
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3
sys/kern/subr_prf.c
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@ -163,6 +163,7 @@ uprintf(const char *fmt, ...)
goto out;
}
pca.flags = TOTTY;
pca.p_bufr = NULL;
va_start(ap, fmt);
tty_lock(pca.tty);
retval = kvprintf(fmt, putchar, &pca, 10, ap);
@ -206,6 +207,7 @@ tprintf(struct proc *p, int pri, const char *fmt, ...)
pca.pri = pri;
pca.tty = tp;
pca.flags = flags;
pca.p_bufr = NULL;
va_start(ap, fmt);
if (pca.tty != NULL)
tty_lock(pca.tty);
@ -234,6 +236,7 @@ ttyprintf(struct tty *tp, const char *fmt, ...)
va_start(ap, fmt);
pca.tty = tp;
pca.flags = TOTTY;
pca.p_bufr = NULL;
retval = kvprintf(fmt, putchar, &pca, 10, ap);
va_end(ap);
return (retval);