On Wed, Apr 24, 2019 at 11:50:22PM +0200, Christian Brauner wrote: > On Wed, Apr 24, 2019 at 7:16 PM Greg Kroah-Hartman > <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > > > [ Upstream commit 32a5ad9c22852e6bd9e74bdec5934ef9d1480bc5 ] > > > > Currently, when writing > > > > echo 18446744073709551616 > /proc/sys/fs/file-max > > > > /proc/sys/fs/file-max will overflow and be set to 0. That quickly > > crashes the system. > > > > This commit sets the max and min value for file-max. The max value is > > set to long int. Any higher value cannot currently be used as the > > percpu counters are long ints and not unsigned integers. > > > > Note that the file-max value is ultimately parsed via > > __do_proc_doulongvec_minmax(). This function does not report error when > > min or max are exceeded. Which means if a value largen that long int is > > written userspace will not receive an error instead the old value will be > > kept. There is an argument to be made that this should be changed and > > __do_proc_doulongvec_minmax() should return an error when a dedicated min > > or max value are exceeded. However this has the potential to break > > userspace so let's defer this to an RFC patch. > > > > Link: http://lkml.kernel.org/r/20190107222700.15954-3-christian@xxxxxxxxxx > > Signed-off-by: Christian Brauner <christian@xxxxxxxxxx> > > Acked-by: Kees Cook <keescook@xxxxxxxxxxxx> > > Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx> > > Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> > > Cc: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx> > > Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> > > Cc: Joe Lawrence <joe.lawrence@xxxxxxxxxx> > > Cc: Luis Chamberlain <mcgrof@xxxxxxxxxx> > > Cc: Waiman Long <longman@xxxxxxxxxx> > > [christian@xxxxxxxxxx: v4] > > Link: http://lkml.kernel.org/r/20190210203943.8227-3-christian@xxxxxxxxxx > > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > > Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> > > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> > > Hey Greg, > > Just an heads-up. This patch triggered a KASAN warning and Will has > sent a fix for that > which is already in master. > So if you backport this patch you likely also want to backport > > 9002b21465fa4d829edfc94a5a441005cffaa972 > > (See https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9002b21465fa4d829edfc94a5a441005cffaa972 > ) > > Seems we missed a Cc: for stable in there. Sorry about that. No problem, thanks for letting me know, now queued up everywhere. greg k-h
