CVE-2026-23378: net/sched: act_ife: Fix metalist update behavior

In the Linux kernel, the following vulnerability has been resolved:

net/sched: actife: Fix metalist update behavior

Whenever an ife action replace changes the metalist, instead of replacing the old data on the metalist, the current ife code is appending the new metadata. Aside from being innapropriate behavior, this may lead to an unbounded addition of metadata to the metalist which might cause an out of bounds error when running the encode op:

[ 138.423369][ C1] ================================================================== [ 138.424317][ C1] BUG: KASAN: slab-out-of-bounds in ifetlvmetaencode (net/ife/ife.c:168) [ 138.424906][ C1] Write of size 4 at addr ffff8880077f4ffe by task ifeoutoutbou/255 [ 138.425778][ C1] CPU: 1 UID: 0 PID: 255 Comm: ifeoutoutbou Not tainted 7.0.0-rc1-00169-gfbdfa8da05b6 #624 PREEMPT(full) [ 138.425795][ C1] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 138.425800][ C1] Call Trace: [ 138.425804][ C1] <IRQ> [ 138.425808][ C1] dumpstacklvl (lib/dumpstack.c:122) [ 138.425828][ C1] printreport (mm/kasan/report.c:379 mm/kasan/report.c:482) [ 138.425839][ C1] ? srsoaliasreturnthunk (arch/x86/lib/retpoline.S:221) [ 138.425844][ C1] ? virtaddrvalid (./arch/x86/include/asm/preempt.h:95 (discriminator 1) ./include/linux/rcupdate.h:975 (discriminator 1) ./include/linux/mmzone.h:2207 (discriminator 1) arch/x86/mm/physaddr.c:54 (discriminator 1)) [ 138.425853][ C1] ? ifetlvmetaencode (net/ife/ife.c:168) [ 138.425859][ C1] kasanreport (mm/kasan/report.c:221 mm/kasan/report.c:597) [ 138.425868][ C1] ? ifetlvmetaencode (net/ife/ife.c:168) [ 138.425878][ C1] kasancheckrange (mm/kasan/generic.c:186 (discriminator 1) mm/kasan/generic.c:200 (discriminator 1)) [ 138.425884][ C1] asanmemset (mm/kasan/shadow.c:84 (discriminator 2)) [ 138.425889][ C1] ifetlvmetaencode (net/ife/ife.c:168) [ 138.425893][ C1] ? ifetlvmetaencode (net/ife/ife.c:171) [ 138.425898][ C1] ? srsoaliasreturnthunk (arch/x86/lib/retpoline.S:221) [ 138.425903][ C1] ifeencodemetau16 (net/sched/actife.c:57) [ 138.425910][ C1] ? pfxdorawspinlock (kernel/locking/spinlockdebug.c:114) [ 138.425916][ C1] ? asanmemcpy (mm/kasan/shadow.c:105 (discriminator 3)) [ 138.425921][ C1] ? pfxifeencodemetau16 (net/sched/actife.c:45) [ 138.425927][ C1] ? srsoaliasreturnthunk (arch/x86/lib/retpoline.S:221) [ 138.425931][ C1] tcfifeact (net/sched/actife.c:847 net/sched/actife.c:879)

To solve this issue, fix the replace behavior by adding the metalist to the ife rcu data structure.