CVE-2024-58070

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

bpf: bpflocalstorage: Always use bpfmemalloc in PREEMPT_RT

In PREEMPTRT, kmalloc(GFPATOMIC) is still not safe in non preemptible context. bpfmemalloc must be used in PREEMPTRT. This patch is to enforce bpfmemalloc in the bpflocalstorage when CONFIGPREEMPT_RT is enabled.

[ 35.118559] BUG: sleeping function called from invalid context at kernel/locking/spinlockrt.c:48 [ 35.118566] inatomic(): 1, irqsdisabled(): 0, nonblock: 0, pid: 1832, name: testprogs [ 35.118569] preemptcount: 1, expected: 0 [ 35.118571] RCU nest depth: 1, expected: 1 [ 35.118577] INFO: lockdep is turned off. ... [ 35.118647] mightresched+0x433/0x5b0 [ 35.118677] rtspinlock+0xc3/0x290 [ 35.118700] _slaballoc+0x72/0xc40 [ 35.118723] _kmallocnoprof+0x13f/0x4e0 [ 35.118732] bpfmapkzalloc+0xe5/0x220 [ 35.118740] bpfselemalloc+0x1d2/0x7b0 [ 35.118755] bpflocalstorageupdate+0x2fa/0x8b0 [ 35.118784] bpfskstoragegettracing+0x15a/0x1d0 [ 35.118791] bpfprog9a118d86fca78ebbtraceinetsocksetstate+0x44/0x66 [ 35.118795] bpftracerun3+0x222/0x400 [ 35.118820] _bpftraceinetsocksetstate+0x11/0x20 [ 35.118824] traceinetsocksetstate+0x112/0x130 [ 35.118830] inetskstatestore+0x41/0x90 [ 35.118836] tcpset_state+0x3b3/0x640

There is no need to adjust the gfpflags passing to the bpfmemcacheallocflags() which only honors the GFPKERNEL. The verifier has ensured GFP_KERNEL is passed only in sleepable context.

It has been an old issue since the first introduction of the bpflocalstorage ~5 years ago, so this patch targets the bpf-next.

bpfmemalloc is needed to solve it, so the Fixes tag is set to the commit when bpfmemalloc was first used in the bpflocalstorage.