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authorJiri Slaby <jslaby@suse.cz>2015-02-27 18:40:31 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-03-07 03:06:51 +0100
commitf0bf0bd07943bfde8f5ac39a32664810a379c7d3 (patch)
treebd55289965c449cadab342b0e57fe549dc9cb3eb /drivers
parentdfd37668ea6d5029fb5d8a66ea5e202d0655fad7 (diff)
downloadkernel-f0bf0bd07943bfde8f5ac39a32664810a379c7d3.tar.gz
tty: fix up atime/mtime mess, take four
This problem was taken care of three times already in * b0de59b5733d18b0d1974a060860a8b5c1b36a2e (TTY: do not update atime/mtime on read/write), * 37b7f3c76595e23257f61bd80b223de8658617ee (TTY: fix atime/mtime regression), and * b0b885657b6c8ef63a46bc9299b2a7715d19acde (tty: fix up atime/mtime mess, take three) But it still misses one point. As John Paul correctly points out, we do not care about setting date. If somebody ever changes wall time backwards (by mistake for example), tty timestamps are never updated until the original wall time passes. So check the absolute difference of times and if it large than "8 seconds or so", always update the time. That means we will update immediatelly when changing time. Ergo, CAP_SYS_TIME can foul the check, but it was always that way. Thanks John for serving me this so nicely debugged. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Reported-by: John Paul Perry <john_paul.perry@alcatel-lucent.com> Cc: <stable@vger.kernel.org> # all, as b0b885657 was backported Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/tty/tty_io.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 51f066aa375e..2bb4dfc02873 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1028,8 +1028,8 @@ EXPORT_SYMBOL(start_tty);
/* We limit tty time update visibility to every 8 seconds or so. */
static void tty_update_time(struct timespec *time)
{
- unsigned long sec = get_seconds() & ~7;
- if ((long)(sec - time->tv_sec) > 0)
+ unsigned long sec = get_seconds();
+ if (abs(sec - time->tv_sec) & ~7)
time->tv_sec = sec;
}