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

[Joel Granados]

On Mon, Feb 24, 2025 at 10:58:15AM +0100, nicolas.bouchinet@xxxxxxxxxxx wrote:
> From: Nicolas Bouchinet <nicolas.bouchinet@xxxxxxxxxxx>
> 
> 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@xxxxxxxxxxx/
> 
> 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@xxxxxxxxxxx/
> 
> * 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@xxxxxxxxxxx/
> [4]: https://lore.kernel.org/all/20250128103821.29745-1-nicolas.bouchinet@xxxxxxxxxxx/
> 
> ---
> 
> 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