On Fri, 14 Aug 2026 12:41:11 +0200 Joel Granados <[email protected]>
wrote:
> What?
> =====
>
> Stage table->data when writing INT & ULONG ctl_tables. Commit staged
> data to kernel variable only when all the conversions have succeeded.
> This is applicable only to variables that represent a vector; paths
> pertaining to scalers are left unchanged. Notice that partial updates
"scalars"
> can still happen if less than the size of the vector are passed and
> correctly formatted.
>
> This is the behavior we are protecting against:
>
> # echo "4 4 1 7" > /proc/sys/kernel/printk
> # echo "1 x" > /proc/sys/kernel/printk
> -bash: echo: write error: Invalid argument
> # cat /proc/sys/kernel/printk
> 1 4 1 7 <- the write failed, the first element changed anyway
I like the change.
> Why?
> ====
> Allowing a partial change to a vector after returning from an erroneous
> proc_handler is just plain wrong. This should be handled within sysctl
> to avoid users having to do it for themselves [1].
>
> Behavioral Changes
> ==================
> 1. A failed write will not update the vector
> 2. Vector writes can now fail with -ENOMEM
Yeah, this improves Linux.
> Testing
> =======
> This went through regular sysctl kunit and self test. Also is posted to
> 0-day.
>
> I always find it difficult to know who wants to receive this. Please let
> me know if you want to be removed from the Cc/To.
Sashiko said one thing:
https://sashiko.dev/#/patchset/[email protected]
