Hey Andrew, You currently carry * sysctl-handle-overflow-in-proc_get_long.patch * sysctl-handle-overflow-for-file-max.patch in your http://www.ozlabs.org/~akpm/mmotm/ tree. I recently pointed out that the current change can potentially lead to a userspace facing change and asked you to please drop the second patch (cf. [3]). I think you might have missed that mail. This is the same patchset just that the userspace facing change is split out into a separate commit. Please take the first two commits as they fix the issue without any userspace facing change. The third one is marked as RFC and we can either take it now or punt on it until later. 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. The first version of this patch intended to detect the overflow and cap at ULONG_MAX. However, we should not do this and rather return EINVAL on overflow. The reasons are: - this aligns with other sysctl handlers that simply reject overflows (cf. [1], [2], and a bunch of others) - we already do a partial fail on overflow right now Namely, when the TMPBUFLEN is exceeded. So we already reject values such as 184467440737095516160 (21 chars) but accept values such as 18446744073709551616 (20 chars) but both are overflows. So we should just always reject 64bit overflows and not special-case this based on the number of chars. (This patchset is in reference to https://lkml.org/lkml/2018/10/11/585.) Thanks! Christian [1]: fb910c42cceb ("sysctl: check for UINT_MAX before unsigned int min/max") [2]: 196851bed522 ("s390/topology: correct topology mode proc handler") [3]: https://lore.kernel.org/lkml/20190111145140.lbmiz3w2f255uf65@xxxxxxxxxx/ Christian Brauner (3): sysctl: handle overflow in proc_get_long sysctl: handle overflow for file-max sysctl: return -EINVAL if val violates minmax kernel/sysctl.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 46 insertions(+), 3 deletions(-) -- 2.20.1
