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Fix decoding of sysctl() when oldval fields are NULL

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If you call glibc's syscall wrapper like so:
	static int name[] = { CTL_NET, NET_IPV4, NET_IPV4_LOCAL_PORT_RANGE };
	int buffer[2] = { 32768, 61000 };
	size_t size = sizeof(buffer);
	sysctl(name, 3, 0, 0, buffer, size);
(note that oldval/oldlenp are NULL).

The current strace code complains like so:
_sysctl({{CTL_NET, NET_IPV4, NET_IPV4_LOCAL_PORT_RANGE, 38}, 3, process_vm_readv: Bad address
(nil), 0, 0x7fffe23c3960, 8}) = -1 EACCES (Permission denied)

Since passing NULL for the old values is valid, handle that explicitly.
This also simplifies the code a bit by splitting up the handling of the
new and old args so that we only handle the new args once.

Now the output looks like:
_sysctl({{CTL_NET, NET_IPV4, NET_IPV4_LOCAL_PORT_RANGE, 38}, 3, NULL, 0, 0x7fff8c0c91b0, 8) = -1 EACCES (Permission denied)

* system.c (sys_sysctl): Check if info.oldval is NULL first.  Move the
processing of oldlen/info.newval/info.newlen out so they always get
executed.  Fix the format strings so we use %lu for unsigned long rather
than a mix of %ld and %lu.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
This commit is contained in:
Mike Frysinger 2013-02-08 19:10:07 -05:00 committed by Dmitry V. Levin
parent 99aa181ebc
commit 0cf04b6595
1 changed files with 19 additions and 19 deletions
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38
system.c
View File

@ -954,32 +954,32 @@ sys_sysctl(struct tcb *tcp)
tprintf("}, %d, ", info.nlen);
} else {
size_t oldlen = 0;
if (umove(tcp, (long)info.oldlenp, &oldlen) >= 0
&& info.nlen >= 2
&& ((name[0] == CTL_KERN
&& (name[1] == KERN_OSRELEASE
|| name[1] == KERN_OSTYPE
if (info.oldval == NULL) {
tprints("NULL");
} else if (umove(tcp, (long)info.oldlenp, &oldlen) >= 0
&& info.nlen >= 2
&& ((name[0] == CTL_KERN
&& (name[1] == KERN_OSRELEASE
|| name[1] == KERN_OSTYPE
#ifdef KERN_JAVA_INTERPRETER
|| name[1] == KERN_JAVA_INTERPRETER
|| name[1] == KERN_JAVA_INTERPRETER
#endif
#ifdef KERN_JAVA_APPLETVIEWER
|| name[1] == KERN_JAVA_APPLETVIEWER
|| name[1] == KERN_JAVA_APPLETVIEWER
#endif
)))) {
)))) {
printpath(tcp, (size_t)info.oldval);
tprintf(", %lu, ", (unsigned long)oldlen);
if (info.newval == 0)
tprints("NULL");
else if (syserror(tcp))
tprintf("%p", info.newval);
else
printpath(tcp, (size_t)info.newval);
tprintf(", %ld}", (unsigned long)info.newlen);
} else {
tprintf("%p, %ld, %p, %ld}",
info.oldval, (unsigned long)oldlen,
info.newval, (unsigned long)info.newlen);
tprintf("%p", info.oldval);
}
tprintf(", %lu, ", (unsigned long)oldlen);
if (info.newval == NULL)
tprints("NULL");
else if (syserror(tcp))
tprintf("%p", info.newval);
else
printpath(tcp, (size_t)info.newval);
tprintf(", %lu", (unsigned long)info.newlen);
}
free(name);