Commit e35659f1 authored Dec 21, 2016 by NeilBrown Committed by J. Bruce Fields Jan 31, 2017

NFSD: correctly range-check v4.x minor version when setting versions.



Writing to /proc/fs/nfsd/versions allows individual major versions
and NFSv4 minor versions to be enabled or disabled.

However NFSv4.0 cannot currently be disabled, thought there is no good reason.
Also the minor number is parsed as a 'long' but used as an 'int'
so '4294967297' will be incorrectly treated as '1'.

This patch removes the test on 'minor == 0' and switches to kstrtouint()
to get correct range checking.

When reading from /proc/fs/nfsd/versions, 4.0 is current not reported.
To allow the disabling for v4.0 to be visible, while maintaining
backward compatibility, change code to report "-4.0" if appropriate, but
not "+4.0".

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

parent 2b477c00

fs/nfsd/nfsctl.c

+7 −3

Original line number	Diff line number	Diff line
		@@ -569,8 +569,7 @@ static ssize_t __write_versions(struct file file, char buf, size_t size)
		if (*minorp == '.') {
		if (num != 4)
		return -EINVAL;
		minor = simple_strtoul(minorp+1, NULL, 0);
		if (minor == 0)
		if (kstrtouint(minorp+1, 0, &minor) < 0)
		return -EINVAL;
		if (nfsd_minorversion(minor, sign == '-' ?
		NFSD_CLEAR : NFSD_SET) < 0)
		@@ -613,8 +612,13 @@ static ssize_t __write_versions(struct file file, char buf, size_t size)
		tlen += len;
		}
		if (nfsd_vers(4, NFSD_AVAIL))
		for (minor = 1; minor <= NFSD_SUPPORTED_MINOR_VERSION;
		for (minor = 0; minor <= NFSD_SUPPORTED_MINOR_VERSION;
		minor++) {
		if (minor == 0 && nfsd_minorversion(minor, NFSD_TEST))
		/* for backward compatibility, don't report
		* +4.0
		*/
		continue;
		len = snprintf(buf, remaining, " %c4.%u",
		(nfsd_vers(4, NFSD_TEST) &&
		nfsd_minorversion(minor, NFSD_TEST)) ?

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