On Fri, Nov 01, 2024 at 03:09:33AM -0700, Breno Leitao wrote: > diff --git a/Documentation/fault-injection/fault-injection.rst b/Documentation/fault-injection/fault-injection.rst > index 8b8aeea71c685b358dfebb419ae74277e729298a..880237dca4ff78e7f11dac3cca70969a18a70cc3 100644 > --- a/Documentation/fault-injection/fault-injection.rst > +++ b/Documentation/fault-injection/fault-injection.rst > @@ -45,6 +45,32 @@ Available fault injection capabilities > ALLOW_ERROR_INJECTION() macro, by setting debugfs entries > under /sys/kernel/debug/fail_function. No boot option supported. > > +- fail_skb_realloc > + > + inject skb (socket buffer) reallocation events into the network path. The > + primary goal is to identify and prevent issues related to pointer > + mismanagement in the network subsystem. By forcing skb reallocation at > + strategic points, this feature creates scenarios where existing pointers to > + skb headers become invalid. > + > + When the fault is injected and the reallocation is triggered, cached pointers > + to skb headers and data no longer reference valid memory locations. This > + deliberate invalidation helps expose code paths where proper pointer updating > + is neglected after a reallocation event. > + > + By creating these controlled fault scenarios, the system can catch instances > + where stale pointers are used, potentially leading to memory corruption or > + system instability. > + > + To select the interface to act on, write the network name to the following file: > + `/sys/kernel/debug/fail_skb_realloc/devname` "... write the network name to /sys/kernel/debug/fail_skb_realloc/devname." > + If this field is left empty (which is the default value), skb reallocation > + will be forced on all network interfaces. > + > + The effectiveness of this fault detection is enhanced when KASAN is > + enabled, as it helps identify invalid memory references and use-after-free > + (UAF) issues. > + > - NVMe fault injection > > inject NVMe status code and retry flag on devices permitted by setting > @@ -216,6 +242,19 @@ configuration of fault-injection capabilities. > use a negative errno, you better use 'printf' instead of 'echo', e.g.: > $ printf %#x -12 > retval > > +- /sys/kernel/debug/fail_skb_realloc/devname: > + > + Specifies the network interface on which to force SKB reallocation. If > + left empty, SKB reallocation will be applied to all network interfaces. > + > + Example usage:: > + > + # Force skb reallocation on eth0 > + echo "eth0" > /sys/kernel/debug/fail_skb_realloc/devname > + > + # Clear the selection and force skb reallocation on all interfaces > + echo "" > /sys/kernel/debug/fail_skb_realloc/devname > + The rest of docs changes looks good. Thanks. -- An old man doll... just what I always wanted! - Clara
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