CVE-2024-56701

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

powerpc/pseries: Fix dtlaccesslock to be a rw_semaphore

The dtlaccesslock needs to be a rw_sempahore, a sleeping lock, because the code calls kmalloc() while holding it, which can sleep:

# echo 1 > /proc/powerpc/vcpudispatchstats BUG: sleeping function called from invalid context at include/linux/sched/mm.h:337 inatomic(): 1, irqsdisabled(): 0, nonblock: 0, pid: 199, name: sh preemptcount: 1, expected: 0 3 locks held by sh/199: #0: c00000000a0743f8 (sbwriters#3){.+.+}-{0:0}, at: vfswrite+0x324/0x438 #1: c0000000028c7058 (dtlenablemutex){+.+.}-{3:3}, at: vcpudispatchstatswrite+0xd4/0x5f4 #2: c0000000028c70b8 (dtlaccesslock){+.+.}-{2:2}, at: vcpudispatchstatswrite+0x220/0x5f4 CPU: 0 PID: 199 Comm: sh Not tainted 6.10.0-rc4 #152 Hardware name: IBM pSeries (emulated by qemu) POWER9 (raw) 0x4e1202 0xf000005 of:SLOF,HEAD hv:linux,kvm pSeries Call Trace: dumpstack_lvl+0x130/0x148 (unreliable) __mightresched+0x174/0x410 kmemcacheallocnoprof+0x340/0x3d0 allocdtlbuffers+0x124/0x1ac vcpudispatchstatswrite+0x2a8/0x5f4 procregwrite+0xf4/0x150 vfswrite+0xfc/0x438 ksyswrite+0x88/0x148 systemcallexception+0x1c4/0x5a0 systemcallcommon+0xf4/0x258