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assoc_array: don't call compare_object() on a node
Changes since V1: fixed the description and added KASan warning. In assoc_array_insert_into_terminal_node(), we call the compare_object() method on all non-empty slots, even when they're not leaves, passing a pointer to an unexpected structure to compare_object(). Currently it causes an out-of-bound read access in keyring_compare_object detected by KASan (see below). The issue is easily reproduced with keyutils testsuite. Only call compare_object() when the slot is a leave. KASan warning: ================================================================== BUG: KASAN: slab-out-of-bounds in keyring_compare_object+0x213/0x240 at addr ffff880060a6f838 Read of size 8 by task keyctl/1655 ============================================================================= BUG kmalloc-192 (Not tainted): kasan: bad access detected ----------------------------------------------------------------------------- Disabling lock debugging due to kernel taint INFO: Allocated in assoc_array_insert+0xfd0/0x3a60 age=69 cpu=1 pid=1647 ___slab_alloc+0x563/0x5c0 __slab_alloc+0x51/0x90 kmem_cache_alloc_trace+0x263/0x300 assoc_array_insert+0xfd0/0x3a60 __key_link_begin+0xfc/0x270 key_create_or_update+0x459/0xaf0 SyS_add_key+0x1ba/0x350 entry_SYSCALL_64_fastpath+0x12/0x76 INFO: Slab 0xffffea0001829b80 objects=16 used=8 fp=0xffff880060a6f550 flags=0x3fff8000004080 INFO: Object 0xffff880060a6f740 @offset=5952 fp=0xffff880060a6e5d1 Bytes b4 ffff880060a6f730: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ Object ffff880060a6f740: d1 e5 a6 60 00 88 ff ff 0e 00 00 00 00 00 00 00 ...`............ Object ffff880060a6f750: 02 cf 8e 60 00 88 ff ff 02 c0 8e 60 00 88 ff ff ...`.......`.... Object ffff880060a6f760: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ Object ffff880060a6f770: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ Object ffff880060a6f780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ Object ffff880060a6f790: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ Object ffff880060a6f7a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ Object ffff880060a6f7b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ Object ffff880060a6f7c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ Object ffff880060a6f7d0: 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ Object ffff880060a6f7e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ Object ffff880060a6f7f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ CPU: 0 PID: 1655 Comm: keyctl Tainted: G B 4.5.0-rc4-kasan+ #291 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 0000000000000000 000000001b2800b4 ffff880060a179e0 ffffffff81b60491 ffff88006c802900 ffff880060a6f740 ffff880060a17a10 ffffffff815e2969 ffff88006c802900 ffffea0001829b80 ffff880060a6f740 ffff880060a6e650 Call Trace: [<ffffffff81b60491>] dump_stack+0x85/0xc4 [<ffffffff815e2969>] print_trailer+0xf9/0x150 [<ffffffff815e9454>] object_err+0x34/0x40 [<ffffffff815ebe50>] kasan_report_error+0x230/0x550 [<ffffffff819949be>] ? keyring_get_key_chunk+0x13e/0x210 [<ffffffff815ec62d>] __asan_report_load_n_noabort+0x5d/0x70 [<ffffffff81994cc3>] ? keyring_compare_object+0x213/0x240 [<ffffffff81994cc3>] keyring_compare_object+0x213/0x240 [<ffffffff81bc238c>] assoc_array_insert+0x86c/0x3a60 [<ffffffff81bc1b20>] ? assoc_array_cancel_edit+0x70/0x70 [<ffffffff8199797d>] ? __key_link_begin+0x20d/0x270 [<ffffffff8199786c>] __key_link_begin+0xfc/0x270 [<ffffffff81993389>] key_create_or_update+0x459/0xaf0 [<ffffffff8128ce0d>] ? trace_hardirqs_on+0xd/0x10 [<ffffffff81992f30>] ? key_type_lookup+0xc0/0xc0 [<ffffffff8199e19d>] ? lookup_user_key+0x13d/0xcd0 [<ffffffff81534763>] ? memdup_user+0x53/0x80 [<ffffffff819983ea>] SyS_add_key+0x1ba/0x350 [<ffffffff81998230>] ? key_get_type_from_user.constprop.6+0xa0/0xa0 [<ffffffff828bcf4e>] ? retint_user+0x18/0x23 [<ffffffff8128cc7e>] ? trace_hardirqs_on_caller+0x3fe/0x580 [<ffffffff81004017>] ? trace_hardirqs_on_thunk+0x17/0x19 [<ffffffff828bc432>] entry_SYSCALL_64_fastpath+0x12/0x76 Memory state around the buggy address: ffff880060a6f700: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00 ffff880060a6f780: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc >ffff880060a6f800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ^ ffff880060a6f880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff880060a6f900: fc fc fc fc fc fc 00 00 00 00 00 00 00 00 00 00 ================================================================== Signed-off-by: Jerome Marchand <jmarchan@redhat.com> Signed-off-by: David Howells <dhowells@redhat.com> cc: stable@vger.kernel.org
This commit is contained in:
Jerome Marchand
David Howells
parent
541d8f4d59
commit
8d4a2ec1e0
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@ -524,7 +524,9 @@ static bool assoc_array_insert_into_terminal_node(struct assoc_array_edit *edit,
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free_slot = i;
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continue;
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}
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if (ops->compare_object(assoc_array_ptr_to_leaf(ptr), index_key)) {
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if (assoc_array_ptr_is_leaf(ptr) &&
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ops->compare_object(assoc_array_ptr_to_leaf(ptr),
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index_key)) {
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pr_devel("replace in slot %d\n", i);
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edit->leaf_p = &node->slots[i];
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edit->dead_leaf = node->slots[i];
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