Commit 8d060877 authored Feb 10, 2007 by Oleg Nesterov Committed by Linus Torvalds Feb 11, 2007

[PATCH] _proc_do_string(): fix short reads



If you try to read things like /proc/sys/kernel/osrelease with single-byte
reads, you get just one byte and then EOF.  This is because _proc_do_string()
assumes that the caller is read()ing into a buffer which is large enough to
fit the whole string in a single hit.

Fix.

Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent c75fb88d

kernel/sysctl.c

+12 −4

Original line number	Diff line number	Diff line
		@@ -1687,8 +1687,7 @@ static int _proc_do_string(void* data, int maxlen, int write,
		char __user *p;
		char c;

		if (!data \|\| !maxlen \|\| !*lenp \|\|
		(*ppos && !write)) {
		if (!data \|\| !maxlen \|\| !*lenp) {
		*lenp = 0;
		return 0;
		}
		@@ -1713,6 +1712,15 @@ static int _proc_do_string(void* data, int maxlen, int write,
		len = strlen(data);
		if (len > maxlen)
		len = maxlen;

		if (*ppos > len) {
		*lenp = 0;
		return 0;
		}

		data += *ppos;
		len -= *ppos;

		if (len > *lenp)
		len = *lenp;
		if (len)

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