Re: [PATCH v2 0/6] Fixes multiple sysctl bound checks

Joel Granados
2025-03-04T10:33:41Z

On Mon, Feb 24, 2025 at 10:58:15AM +0100, nicolas.bouchinet@clip-os.org wrote:
> From: Nicolas Bouchinet <nicolas.bouchinet@ssi.gouv.fr>
>
> Hi,
>
> This patchset adds some bound checks to sysctls to avoid negative
> value writes.
>
> The patched sysctls were storing the result of the proc_dointvec
> proc_handler into an unsigned int data. proc_dointvec being able to
> parse negative value, and it return value being a signed int, this could
> lead to undefined behaviors.
> This has led to kernel crash in the past as described in commit
> 3b3376f222e3 ("sysctl.c: fix underflow value setting risk in vm_table")
This patch is slightly different then what you are trying to do here.
Notice that the issue in 3b3376f222e3 ("sysctl.c: fix underflow value
setting risk in vm_table") was that the extra1 value was getting ignored
because it was calling proc_dointvec; replacing it with
proc_dointvec_minmax properly forwards the extra1 value.
What your series is trying to do is to avoid a assignment of a negative
value to a unsigned int.
>
> They are now bounded between SYSCTL_ZERO and SYSCTL_INT_MAX.
> The proc_handlers have thus been updated to proc_dointvec_minmax.
>
> This patchset has been written over sysctl-testing branch [1].
> See [2] for similar sysctl fixes currently in review.
>
> [1]: https://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl.git/log/?h=sysctl-testing
> [2]: https://lore.kernel.org/all/20250115132211.25400-1-nicolas.bouchinet@clip-os.org/
>
> Best regards,
>
> Nicolas

In general, I would like for these patches to go into mainline through
their individual subsystem as they would know more about what type fits
best for the ctl_table->data variable. With that said, I'll push the
leftovers through sysctl if there are no takers.

Thx for the series
>
> ---
>
> Changes since v1:
> https://lore.kernel.org/all/20250127142014.37834-1-nicolas.bouchinet@clip-os.org/
>
> * Detached patches 1/9, 2/9 [3] and 3/9 [4]
> * Adapted the cover-letter message to match the reduced patchset
>
> [3]: https://lore.kernel.org/all/20250129170633.88574-1-nicolas.bouchinet@clip-os.org/
> [4]: https://lore.kernel.org/all/20250128103821.29745-1-nicolas.bouchinet@clip-os.org/
>
> ---
>
> Nicolas Bouchinet (6):
> sysctl: Fixes idmap_cache_timeout bounds
> sysctl: Fixes nsm_local_state bounds
> sysctl/coda: Fixes timeout bounds
> sysctl: Fixes scsi_logging_level bounds
> sysctl/infiniband: Fixes infiniband sysctl bounds
> sysctl: Fixes max-user-freq bounds
>
> drivers/char/hpet.c | 4 +++-
> drivers/infiniband/core/iwcm.c | 4 +++-
> drivers/infiniband/core/ucma.c | 4 +++-
> drivers/scsi/scsi_sysctl.c | 4 +++-
> fs/coda/sysctl.c | 4 +++-
> fs/lockd/svc.c | 4 +++-
> fs/nfs/nfs4sysctl.c | 4 +++-
> 7 files changed, 21 insertions(+), 7 deletions(-)
>
> --
> 2.48.1
>

--

Joel Granados