CVE-2022-49081

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

highmem: fix checks in _kmaplocalsched{in,out}

When CONFIGDEBUGKMAP_LOCAL is enabled kmaplocalsched{in,out} check that even slots in the tsk->kmapctrl.pteval are unmapped. The slots are initialized with 0 value, but the check is done with ptenone. 0 pte however does not necessarily mean that ptenone will return true. e.g. on xtensa it returns false, resulting in the following runtime warnings:

WARNING: CPU: 0 PID: 101 at mm/highmem.c:627 __kmaplocalschedout+0x51/0x108 CPU: 0 PID: 101 Comm: touch Not tainted 5.17.0-rc7-00010-gd3a1cdde80d2-dirty #13 Call Trace: dumpstack+0xc/0x40 __warn+0x8f/0x174 warnslowpathfmt+0x48/0xac __kmaplocalsched_out+0x51/0x108 _schedule+0x71a/0x9c4 preemptscheduleirq+0xa0/0xe0 commonexceptionreturn+0x5c/0x93 dowppage+0x30e/0x330 handlemmfault+0xa70/0xc3c dopagefault+0x1d8/0x3c4 commonexception+0x7f/0x7f

WARNING: CPU: 0 PID: 101 at mm/highmem.c:664 __kmaplocalschedin+0x50/0xe0 CPU: 0 PID: 101 Comm: touch Tainted: G W 5.17.0-rc7-00010-gd3a1cdde80d2-dirty #13 Call Trace: dumpstack+0xc/0x40 __warn+0x8f/0x174 warnslowpathfmt+0x48/0xac __kmaplocalschedin+0x50/0xe0 finishtask_switch$isra$0+0x1ce/0x2f8 _schedule+0x86e/0x9c4 preemptscheduleirq+0xa0/0xe0 commonexceptionreturn+0x5c/0x93 dowppage+0x30e/0x330 handlemmfault+0xa70/0xc3c dopagefault+0x1d8/0x3c4 commonexception+0x7f/0x7f

Fix it by replacing !ptenone(pteval) with pteval(pteval) != 0.