[CIFS] Fix setting time before epoch (negative time values) (2ae83bf9) · Commits · 戴 / test

xfstest generic/258 sets the time on a file to a negative value (before 1970) which fails since do_div can not handle negative numbers. In addition 'normal' division of 64 bit values does not build on 32 bit arch so have to workaround this by special casing negative values in cifs_NTtimeToUnix Samba server also has a bug with this (see samba bugzilla 7771) but it works to Windows server. Signed-off-by:

Steve French <smfrench@gmail.com>

fs/cifs/netmisc.c

+16 −4

Original line number	Diff line number	Diff line
		@@ -925,11 +925,23 @@ cifs_NTtimeToUnix(__le64 ntutc)
		/* BB what about the timezone? BB */

		/* Subtract the NTFS time offset, then convert to 1s intervals. */
		u64 t;
		s64 t = le64_to_cpu(ntutc) - NTFS_TIME_OFFSET;

		t = le64_to_cpu(ntutc) - NTFS_TIME_OFFSET;
		ts.tv_nsec = do_div(t, 10000000) * 100;
		/*
		* Unfortunately can not use normal 64 bit division on 32 bit arch, but
		* the alternative, do_div, does not work with negative numbers so have
		* to special case them
		*/
		if (t < 0) {
		t = -t;
		ts.tv_nsec = (long)(do_div(t, 10000000) * 100);
		ts.tv_nsec = -ts.tv_nsec;
		ts.tv_sec = -t;
		} else {
		ts.tv_nsec = (long)do_div(t, 10000000) * 100;
		ts.tv_sec = t;
		}

		return ts;
		}

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