Re: [PATCH v2 0/4] sysctl: Disallow partial updates of miss-formatted sysctl vectors
Andrew Morton <[email protected]>
| Newsgroups | org.kernel.vger.linux-kselftest,org.kernel.vger.linux-fsdevel,org.kernel.vger.linux-kernel,org.kvack.linux-mm |
|---|---|
| Message-ID | <[email protected]> |
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]