Re: [RFC PATCH v1] powerpc: Enable KFENCE for PPC32

From: Christophe Leroy
Date: Thu Mar 04 2021 - 06:25:41 EST



Le 03/03/2021 à 11:56, Marco Elver a écrit :

Somewhat tangentially, I also note that e.g. show_regs(regs) (which
was printed along the KFENCE report above) didn't include the top
frame in the "Call Trace", so this assumption is definitely not
isolated to KFENCE.


Now, I have tested PPC64 (with the patch I sent yesterday to modify save_stack_trace_regs() applied), and I get many failures. Any idea ?

[ 17.653751][ T58] ==================================================================
[ 17.654379][ T58] BUG: KFENCE: invalid free in .kfence_guarded_free+0x2e4/0x530
[ 17.654379][ T58]
[ 17.654831][ T58] Invalid free of 0xc00000003c9c0000 (in kfence-#77):
[ 17.655358][ T58] .kfence_guarded_free+0x2e4/0x530
[ 17.655775][ T58] .__slab_free+0x320/0x5a0
[ 17.656039][ T58] .test_double_free+0xe0/0x198
[ 17.656308][ T58] .kunit_try_run_case+0x80/0x110
[ 17.656523][ T58] .kunit_generic_run_threadfn_adapter+0x38/0x50
[ 17.657161][ T58] .kthread+0x18c/0x1a0
[ 17.659148][ T58] .ret_from_kernel_thread+0x58/0x70
[ 17.659869][ T58]
[ 17.663954][ T58] kfence-#77 [0xc00000003c9c0000-0xc00000003c9c001f, size=32, cache=kmalloc-32] allocated by task 58:
[ 17.666113][ T58] .__kfence_alloc+0x1bc/0x510
[ 17.667069][ T58] .__kmalloc+0x280/0x4f0
[ 17.667452][ T58] .test_alloc+0x19c/0x430
[ 17.667732][ T58] .test_double_free+0x88/0x198
[ 17.667971][ T58] .kunit_try_run_case+0x80/0x110
[ 17.668283][ T58] .kunit_generic_run_threadfn_adapter+0x38/0x50
[ 17.668553][ T58] .kthread+0x18c/0x1a0
[ 17.669315][ T58] .ret_from_kernel_thread+0x58/0x70
[ 17.669711][ T58]
[ 17.669711][ T58] freed by task 58:
[ 17.670116][ T58] .kfence_guarded_free+0x3d0/0x530
[ 17.670421][ T58] .__slab_free+0x320/0x5a0
[ 17.670603][ T58] .test_double_free+0xb4/0x198
[ 17.670827][ T58] .kunit_try_run_case+0x80/0x110
[ 17.671073][ T58] .kunit_generic_run_threadfn_adapter+0x38/0x50
[ 17.671410][ T58] .kthread+0x18c/0x1a0
[ 17.671618][ T58] .ret_from_kernel_thread+0x58/0x70
[ 17.671972][ T58]
[ 17.672638][ T58] CPU: 0 PID: 58 Comm: kunit_try_catch Tainted: G B 5.12.0-rc1-01540-g0783285cc1b8-dirty #4685
[ 17.673768][ T58] ==================================================================
[ 17.677031][ T58] # test_double_free: EXPECTATION FAILED at mm/kfence/kfence_test.c:380
[ 17.677031][ T58] Expected report_matches(&expect) to be true, but is false
[ 17.684397][ T1] not ok 7 - test_double_free
[ 17.686463][ T59] # test_double_free-memcache: setup_test_cache: size=32, ctor=0x0
[ 17.688403][ T59] # test_double_free-memcache: test_alloc: size=32, gfp=cc0, policy=any, cache=1
[ 17.797584][ T59] ==================================================================
[ 17.801260][ T59] BUG: KFENCE: invalid free in .kfence_guarded_free+0x2e4/0x530
[ 17.801260][ T59]
[ 17.801512][ T59] Invalid free of 0xc00000003c9effe0 (in kfence-#78):
[ 17.801668][ T59] .kfence_guarded_free+0x2e4/0x530
[ 17.801849][ T59] .__slab_free+0x320/0x5a0
[ 17.801983][ T59] .kmem_cache_free+0x31c/0x5c0
[ 17.802109][ T59] .test_double_free+0xd0/0x198
[ 17.802227][ T59] .kunit_try_run_case+0x80/0x110
[ 17.802494][ T59] .kunit_generic_run_threadfn_adapter+0x38/0x50
[ 17.802641][ T59] .kthread+0x18c/0x1a0
[ 17.802821][ T59] .ret_from_kernel_thread+0x58/0x70
[ 17.802989][ T59]
[ 17.803303][ T59] kfence-#78 [0xc00000003c9effe0-0xc00000003c9effff, size=32, cache=test] allocated by task 59:
[ 17.803666][ T59] .__kfence_alloc+0x1bc/0x510
[ 17.803898][ T59] .kmem_cache_alloc+0x290/0x440
[ 17.804036][ T59] .test_alloc+0x188/0x430
[ 17.804151][ T59] .test_double_free+0x88/0x198
[ 17.804363][ T59] .kunit_try_run_case+0x80/0x110
[ 17.804637][ T59] .kunit_generic_run_threadfn_adapter+0x38/0x50
[ 17.805099][ T59] .kthread+0x18c/0x1a0
[ 17.805313][ T59] .ret_from_kernel_thread+0x58/0x70
[ 17.806035][ T59]
[ 17.806035][ T59] freed by task 59:
[ 17.806495][ T59] .kfence_guarded_free+0x3d0/0x530
[ 17.806689][ T59] .__slab_free+0x320/0x5a0
[ 17.806941][ T59] .kmem_cache_free+0x31c/0x5c0
[ 17.807122][ T59] .test_double_free+0xa8/0x198
[ 17.807360][ T59] .kunit_try_run_case+0x80/0x110
[ 17.807538][ T59] .kunit_generic_run_threadfn_adapter+0x38/0x50
[ 17.807703][ T59] .kthread+0x18c/0x1a0
[ 17.808015][ T59] .ret_from_kernel_thread+0x58/0x70
[ 17.808220][ T59]
[ 17.808406][ T59] CPU: 0 PID: 59 Comm: kunit_try_catch Tainted: G B 5.12.0-rc1-01540-g0783285cc1b8-dirty #4685
[ 17.808670][ T59] ==================================================================
[ 17.809882][ T59] # test_double_free-memcache: EXPECTATION FAILED at mm/kfence/kfence_test.c:380
[ 17.809882][ T59] Expected report_matches(&expect) to be true, but is false
[ 17.812462][ T1] not ok 8 - test_double_free-memcache
[ 17.813872][ T60] # test_invalid_addr_free: test_alloc: size=32, gfp=cc0, policy=any, cache=0
[ 17.920432][ T60] ==================================================================
[ 17.920747][ T60] BUG: KFENCE: invalid free in .kfence_guarded_free+0x2e4/0x530
[ 17.920747][ T60]
[ 17.921003][ T60] Invalid free of 0xc00000003ca0ffe1 (in kfence-#79):
[ 17.921137][ T60] .kfence_guarded_free+0x2e4/0x530
[ 17.921268][ T60] .__slab_free+0x320/0x5a0
[ 17.921461][ T60] .test_invalid_addr_free+0xc0/0x1a8
[ 17.921607][ T60] .kunit_try_run_case+0x80/0x110
[ 17.921739][ T60] .kunit_generic_run_threadfn_adapter+0x38/0x50
[ 17.921946][ T60] .kthread+0x18c/0x1a0
[ 17.922065][ T60] .ret_from_kernel_thread+0x58/0x70
[ 17.922215][ T60]
[ 17.922327][ T60] kfence-#79 [0xc00000003ca0ffe0-0xc00000003ca0ffff, size=32, cache=kmalloc-32] allocated by task 60:
[ 17.922585][ T60] .__kfence_alloc+0x1bc/0x510
[ 17.922730][ T60] .__kmalloc+0x280/0x4f0
[ 17.922903][ T60] .test_alloc+0x19c/0x430
[ 17.923032][ T60] .test_invalid_addr_free+0x8c/0x1a8
[ 17.923164][ T60] .kunit_try_run_case+0x80/0x110
[ 17.923333][ T60] .kunit_generic_run_threadfn_adapter+0x38/0x50
[ 17.923489][ T60] .kthread+0x18c/0x1a0
[ 17.923608][ T60] .ret_from_kernel_thread+0x58/0x70
[ 17.923773][ T60]
[ 17.923913][ T60] CPU: 0 PID: 60 Comm: kunit_try_catch Tainted: G B 5.12.0-rc1-01540-g0783285cc1b8-dirty #4685
[ 17.924128][ T60] ==================================================================
[ 17.925133][ T60] # test_invalid_addr_free: EXPECTATION FAILED at mm/kfence/kfence_test.c:397
[ 17.925133][ T60] Expected report_matches(&expect) to be true, but is false
[ 17.927243][ T1] not ok 9 - test_invalid_addr_free
[ 17.931185][ T61] # test_invalid_addr_free-memcache: setup_test_cache: size=32, ctor=0x0
[ 17.932183][ T61] # test_invalid_addr_free-memcache: test_alloc: size=32, gfp=cc0, policy=any, cache=1
[ 18.149594][ T61] ==================================================================
[ 18.149909][ T61] BUG: KFENCE: invalid free in .kfence_guarded_free+0x2e4/0x530
[ 18.149909][ T61]
[ 18.150129][ T61] Invalid free of 0xc00000003ca20001 (in kfence-#80):
[ 18.150267][ T61] .kfence_guarded_free+0x2e4/0x530
[ 18.150465][ T61] .__slab_free+0x320/0x5a0
[ 18.150643][ T61] .kmem_cache_free+0x31c/0x5c0
[ 18.150873][ T61] .test_invalid_addr_free+0xb0/0x1a8
[ 18.151097][ T61] .kunit_try_run_case+0x80/0x110
[ 18.151286][ T61] .kunit_generic_run_threadfn_adapter+0x38/0x50
[ 18.151578][ T61] .kthread+0x18c/0x1a0
[ 18.151762][ T61] .ret_from_kernel_thread+0x58/0x70
[ 18.152085][ T61]
[ 18.152260][ T61] kfence-#80 [0xc00000003ca20000-0xc00000003ca2001f, size=32, cache=test] allocated by task 61:
[ 18.152660][ T61] .__kfence_alloc+0x1bc/0x510
[ 18.152883][ T61] .kmem_cache_alloc+0x290/0x440
[ 18.153128][ T61] .test_alloc+0x188/0x430
[ 18.153325][ T61] .test_invalid_addr_free+0x8c/0x1a8
[ 18.153584][ T61] .kunit_try_run_case+0x80/0x110
[ 18.153796][ T61] .kunit_generic_run_threadfn_adapter+0x38/0x50
[ 18.154094][ T61] .kthread+0x18c/0x1a0
[ 18.154279][ T61] .ret_from_kernel_thread+0x58/0x70
[ 18.154555][ T61]
[ 18.154762][ T61] CPU: 0 PID: 61 Comm: kunit_try_catch Tainted: G B 5.12.0-rc1-01540-g0783285cc1b8-dirty #4685
[ 18.155179][ T61] ==================================================================
[ 18.157795][ T61] # test_invalid_addr_free-memcache: EXPECTATION FAILED at mm/kfence/kfence_test.c:397
[ 18.157795][ T61] Expected report_matches(&expect) to be true, but is false
[ 18.165055][ T1] not ok 10 - test_invalid_addr_free-memcache
[ 18.166459][ T62] # test_corruption: test_alloc: size=32, gfp=cc0, policy=left, cache=0
[ 18.514038][ T62] ==================================================================
[ 18.514772][ T62] BUG: KFENCE: memory corruption in .kfence_guarded_free+0x23c/0x530
[ 18.514772][ T62]
[ 18.515235][ T62] Corrupted memory at 0xc00000003ca60020 [ 0x2a . . . . . . . . . . . . . . . ] (in kfence-#82):
[ 18.516308][ T62] .kfence_guarded_free+0x23c/0x530
[ 18.516550][ T62] .__slab_free+0x320/0x5a0
[ 18.516814][ T62] .test_corruption+0xcc/0x248
[ 18.517053][ T62] .kunit_try_run_case+0x80/0x110
[ 18.517347][ T62] .kunit_generic_run_threadfn_adapter+0x38/0x50
[ 18.517609][ T62] .kthread+0x18c/0x1a0
[ 18.517841][ T62] .ret_from_kernel_thread+0x58/0x70
[ 18.518271][ T62]
[ 18.518405][ T62] kfence-#82 [0xc00000003ca60000-0xc00000003ca6001f, size=32, cache=kmalloc-32] allocated by task 62:
[ 18.518858][ T62] .__kfence_alloc+0x1bc/0x510
[ 18.519180][ T62] .__kmalloc+0x280/0x4f0
[ 18.519370][ T62] .test_alloc+0x19c/0x430
[ 18.519583][ T62] .test_corruption+0x94/0x248
[ 18.519864][ T62] .kunit_try_run_case+0x80/0x110
[ 18.520135][ T62] .kunit_generic_run_threadfn_adapter+0x38/0x50
[ 18.520368][ T62] .kthread+0x18c/0x1a0
[ 18.520569][ T62] .ret_from_kernel_thread+0x58/0x70
[ 18.520825][ T62]
[ 18.520990][ T62] CPU: 0 PID: 62 Comm: kunit_try_catch Tainted: G B 5.12.0-rc1-01540-g0783285cc1b8-dirty #4685
[ 18.521803][ T62] ==================================================================
[ 18.523184][ T62] # test_corruption: EXPECTATION FAILED at mm/kfence/kfence_test.c:417
[ 18.523184][ T62] Expected report_matches(&expect) to be true, but is false
[ 18.524015][ T62] # test_corruption: test_alloc: size=32, gfp=cc0, policy=right, cache=0
[ 18.741141][ T62] ==================================================================
[ 18.741476][ T62] BUG: KFENCE: memory corruption in .kfence_guarded_free+0x160/0x530
[ 18.741476][ T62]
[ 18.741746][ T62] Corrupted memory at 0xc00000003ca8ffdf [ 0x2a ] (in kfence-#83):
[ 18.741995][ T62] .kfence_guarded_free+0x160/0x530
[ 18.742140][ T62] .__slab_free+0x320/0x5a0
[ 18.742402][ T62] .test_corruption+0x19c/0x248
[ 18.742586][ T62] .kunit_try_run_case+0x80/0x110
[ 18.742809][ T62] .kunit_generic_run_threadfn_adapter+0x38/0x50
[ 18.743027][ T62] .kthread+0x18c/0x1a0
[ 18.743488][ T62] .ret_from_kernel_thread+0x58/0x70
[ 18.743970][ T62]
[ 18.744156][ T62] kfence-#83 [0xc00000003ca8ffe0-0xc00000003ca8ffff, size=32, cache=kmalloc-32] allocated by task 62:
[ 18.745071][ T62] .__kfence_alloc+0x1bc/0x510
[ 18.746079][ T62] .__kmalloc+0x280/0x4f0
[ 18.746595][ T62] .test_alloc+0x19c/0x430
[ 18.746879][ T62] .test_corruption+0x164/0x248
[ 18.748178][ T62] .kunit_try_run_case+0x80/0x110
[ 18.749636][ T62] .kunit_generic_run_threadfn_adapter+0x38/0x50
[ 18.749949][ T62] .kthread+0x18c/0x1a0
[ 18.750201][ T62] .ret_from_kernel_thread+0x58/0x70
[ 18.750369][ T62]
[ 18.750485][ T62] CPU: 0 PID: 62 Comm: kunit_try_catch Tainted: G B 5.12.0-rc1-01540-g0783285cc1b8-dirty #4685
[ 18.750762][ T62] ==================================================================
[ 18.751578][ T62] # test_corruption: EXPECTATION FAILED at mm/kfence/kfence_test.c:423
[ 18.751578][ T62] Expected report_matches(&expect) to be true, but is false
[ 18.753340][ T1] not ok 11 - test_corruption
[ 18.754944][ T63] # test_corruption-memcache: setup_test_cache: size=32, ctor=0x0
[ 18.756995][ T63] # test_corruption-memcache: test_alloc: size=32, gfp=cc0, policy=left, cache=1
[ 19.109763][ T63] ==================================================================
[ 19.110515][ T63] BUG: KFENCE: memory corruption in .kfence_guarded_free+0x23c/0x530
[ 19.110515][ T63]
[ 19.110978][ T63] Corrupted memory at 0xc00000003cac0020 [ 0x2a . . . . . . . . . . . . . . . ] (in kfence-#85):
[ 19.111848][ T63] .kfence_guarded_free+0x23c/0x530
[ 19.112763][ T63] .__slab_free+0x320/0x5a0
[ 19.113121][ T63] .kmem_cache_free+0x31c/0x5c0
[ 19.113351][ T63] .test_corruption+0xc0/0x248
[ 19.113806][ T63] .kunit_try_run_case+0x80/0x110
[ 19.114019][ T63] .kunit_generic_run_threadfn_adapter+0x38/0x50
[ 19.114173][ T63] .kthread+0x18c/0x1a0
[ 19.114292][ T63] .ret_from_kernel_thread+0x58/0x70
[ 19.114535][ T63]
[ 19.114681][ T63] kfence-#85 [0xc00000003cac0000-0xc00000003cac001f, size=32, cache=test] allocated by task 63:
[ 19.115287][ T63] .__kfence_alloc+0x1bc/0x510
[ 19.115597][ T63] .kmem_cache_alloc+0x290/0x440
[ 19.115875][ T63] .test_alloc+0x188/0x430
[ 19.116456][ T63] .test_corruption+0x94/0x248
[ 19.116689][ T63] .kunit_try_run_case+0x80/0x110
[ 19.117021][ T63] .kunit_generic_run_threadfn_adapter+0x38/0x50
[ 19.117383][ T63] .kthread+0x18c/0x1a0
[ 19.117572][ T63] .ret_from_kernel_thread+0x58/0x70
[ 19.117713][ T63]
[ 19.117816][ T63] CPU: 0 PID: 63 Comm: kunit_try_catch Tainted: G B 5.12.0-rc1-01540-g0783285cc1b8-dirty #4685
[ 19.118706][ T63] ==================================================================
[ 19.119719][ T63] # test_corruption-memcache: EXPECTATION FAILED at mm/kfence/kfence_test.c:417
[ 19.119719][ T63] Expected report_matches(&expect) to be true, but is false
[ 19.120669][ T63] # test_corruption-memcache: test_alloc: size=32, gfp=cc0, policy=right, cache=1
[ 19.339842][ T63] ==================================================================
[ 19.340238][ T63] BUG: KFENCE: memory corruption in .kfence_guarded_free+0x160/0x530
[ 19.340238][ T63]
[ 19.340487][ T63] Corrupted memory at 0xc00000003caeffdf [ 0x2a ] (in kfence-#86):
[ 19.340748][ T63] .kfence_guarded_free+0x160/0x530
[ 19.340885][ T63] .__slab_free+0x320/0x5a0
[ 19.341095][ T63] .kmem_cache_free+0x31c/0x5c0
[ 19.341285][ T63] .test_corruption+0x190/0x248
[ 19.341480][ T63] .kunit_try_run_case+0x80/0x110
[ 19.341921][ T63] .kunit_generic_run_threadfn_adapter+0x38/0x50
[ 19.342298][ T63] .kthread+0x18c/0x1a0
[ 19.342816][ T63] .ret_from_kernel_thread+0x58/0x70
[ 19.343799][ T63]
[ 19.345941][ T63] kfence-#86 [0xc00000003caeffe0-0xc00000003caeffff, size=32, cache=test] allocated by task 63:
[ 19.347301][ T63] .__kfence_alloc+0x1bc/0x510
[ 19.347620][ T63] .kmem_cache_alloc+0x290/0x440
[ 19.347820][ T63] .test_alloc+0x188/0x430
[ 19.348202][ T63] .test_corruption+0x164/0x248
[ 19.348400][ T63] .kunit_try_run_case+0x80/0x110
[ 19.348609][ T63] .kunit_generic_run_threadfn_adapter+0x38/0x50
[ 19.348810][ T63] .kthread+0x18c/0x1a0
[ 19.349131][ T63] .ret_from_kernel_thread+0x58/0x70
[ 19.349429][ T63]
[ 19.349612][ T63] CPU: 0 PID: 63 Comm: kunit_try_catch Tainted: G B 5.12.0-rc1-01540-g0783285cc1b8-dirty #4685
[ 19.349985][ T63] ==================================================================
[ 19.351145][ T63] # test_corruption-memcache: EXPECTATION FAILED at mm/kfence/kfence_test.c:423
[ 19.351145][ T63] Expected report_matches(&expect) to be true, but is false
[ 19.353730][ T1] not ok 12 - test_corruption-memcache
[ 26.350432][ T69] ==================================================================
[ 26.350757][ T69] BUG: KFENCE: memory corruption in .kfence_guarded_free+0x23c/0x530
[ 26.350757][ T69]
[ 26.350961][ T69] Corrupted memory at 0xc00000003cfcfff9 [ 0xac . . . . . . ] (in kfence-#125):
[ 26.351333][ T69] .kfence_guarded_free+0x23c/0x530
[ 26.351517][ T69] .__slab_free+0x320/0x5a0
[ 26.351645][ T69] .test_kmalloc_aligned_oob_write+0x12c/0x1e4
[ 26.351774][ T69] .kunit_try_run_case+0x80/0x110
[ 26.351902][ T69] .kunit_generic_run_threadfn_adapter+0x38/0x50
[ 26.352066][ T69] .kthread+0x18c/0x1a0
[ 26.352180][ T69] .ret_from_kernel_thread+0x58/0x70
[ 26.352294][ T69]
[ 26.352367][ T69] kfence-#125 [0xc00000003cfcffb0-0xc00000003cfcfff8, size=73, cache=kmalloc-96] allocated by task 69:
[ 26.352668][ T69] .__kfence_alloc+0x1bc/0x510
[ 26.352804][ T69] .__kmalloc+0x280/0x4f0
[ 26.352913][ T69] .test_alloc+0x19c/0x430
[ 26.353092][ T69] .test_kmalloc_aligned_oob_write+0x80/0x1e4
[ 26.353290][ T69] .kunit_try_run_case+0x80/0x110
[ 26.353505][ T69] .kunit_generic_run_threadfn_adapter+0x38/0x50
[ 26.353724][ T69] .kthread+0x18c/0x1a0
[ 26.353896][ T69] .ret_from_kernel_thread+0x58/0x70
[ 26.354153][ T69]
[ 26.354309][ T69] CPU: 0 PID: 69 Comm: kunit_try_catch Tainted: G B 5.12.0-rc1-01540-g0783285cc1b8-dirty #4685
[ 26.354714][ T69] ==================================================================
[ 26.355421][ T69] # test_kmalloc_aligned_oob_write: EXPECTATION FAILED at mm/kfence/kfence_test.c:489
[ 26.355421][ T69] Expected report_matches(&expect) to be true, but is false
[ 26.357224][ T1] not ok 18 - test_kmalloc_aligned_oob_write



Christophe