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SubjectRe: [PATCH v3 0/4] A few round_pipe_size() and pipe-max-size fixups

Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>


On Tue, 10 Oct 2017, Joe Lawrence wrote:

> While backporting Michael's "pipe: fix limit handling" patchset to a
> distro-kernel, Mikulas noticed that current upstream pipe limit handling
> contains a few problems:
>
> 1 - procfs signed wrap: echo'ing a large number into
> /proc/sys/fs/pipe-max-size and then cat'ing it back out shows a
> negative value.
>
> 2 - round_pipe_size() nr_pages overflow on 32bit: this would
> subsequently try roundup_pow_of_two(0), which is undefined.
>
> 3 - visible non-rounded pipe-max-size value: there is no mutual
> exclusion or protection between the time pipe_max_size is assigned
> a raw value from proc_dointvec_minmax() and when it is rounded.
>
> 4 - unsigned long -> unsigned int conversion makes for potential odd
> return errors from do_proc_douintvec_minmax_conv() and
> do_proc_dopipe_max_size_conv().
>
> This version underwent the same testing as v1:
> https://marc.info/?l=linux-kernel&m=150643571406022&w=2
>
> v1 (from rfc):
>
> - Re-arrange patchset order, push smaller fixes to the front
> - Add a check so that round_pipe_size(size < pipe_min_size) will round
> up to round_pipe_size(pipe_min_size) as per man page [RD]
> - Add new procfs proc_dopipe_max_size() and helpers to consolidate user
> space read / type validation / rounding / assignment [MP]
>
> v2:
> - Fix !CONFIG_PROC_SYSCTL build case [buildbots]
>
> v3:
> - s/proc_dointvec_minmax/proc_dopipe_max_size/ in comment
> preceding pipe_proc_fn()
> - Added a fourth patch to address -ERANGE vs. -EINVAL inconsistencies in
> do_proc_douintvec_minmax_conv() and do_proc_dopipe_max_size_conv().
>
> Joe Lawrence (4):
> pipe: match pipe_max_size data type with procfs
> pipe: avoid round_pipe_size() nr_pages overflow on 32-bit
> pipe: add proc_dopipe_max_size() to safely assign pipe_max_size
> sysctl: check for UINT_MAX before unsigned int min/max
>
> fs/pipe.c | 23 ++++++++++---------
> include/linux/pipe_fs_i.h | 1 +
> include/linux/sysctl.h | 3 +++
> kernel/sysctl.c | 57 ++++++++++++++++++++++++++++++++++++++++++++---
> 4 files changed, 70 insertions(+), 14 deletions(-)
>
> --
> 1.8.3.1
>

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