In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
RDMA\/rxe: Fix a use-after-free problem in rxe_mmap<\/p>\n
rxe_mmap() removes a rxe_mmap_info struct from the pending_mmaps list
\nand releases pending_lock while the struct’s kref is still at 1:<\/p>\n
list_del_init(&ip->pending_mmaps);
\n spin_unlock_bh(&rxe->pending_lock); \/* ref == 1, no lock held *\/
\n ret = remap_vmalloc_range(vma, ip->obj, 0); \/* walks PTEs *\/
\n […]
\n rxe_vma_open(vma); \/* kref_get, ref \u2192 2 *\/
\n remap_vmalloc_range_partial() walks PTEs without any lock.<\/p>\n
A concurrent DESTROY_CQ ioctl on another CPU calls:<\/p>\n
kref_put(&q->ip->ref, rxe_mmap_release) \/* ref 1\u21920 *\/
\n vfree(ip->obj) \/* clears vmalloc PTEs mid-walk *\/
\n kfree(ip) \/* frees rxe_mmap_info *\/<\/p>\n
This yields:<\/p>\n
1. Kernel crash, vmalloc_to_page() returns NULL when vfree wins the
\n per-PTE race -> vm_insert_page(NULL) \u2192 GPF in validate_page_before_insert<\/p>\n
2. Page UAF, vmalloc_to_page() reads a stale PTE before vfree clears
\n it. User VMA holds a PTE to a free’d page which might eventually get
\n reallocated later by vmalloc which allows the attacker to get a clean
\n page-level UAF.<\/p>\n
It is worth noting that even though a page-level UAF is possible given
\n the strong primitive, it is statistically very difficult to achieve
\n given the very short time window (after the last insert_page and before
\n the kref_get).<\/p>\n
The call trace are as below:<\/p>\n
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] SMP KASAN NOPTI
\n KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
\n CPU: 0 UID: 1000 PID: 413 Comm: poc Not tainted 7.0.0-rc5-dirty #28 PREEMPT(lazy)
\n Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04\/01\/2014
\n RIP: 0010:validate_page_before_insert+0x32\/0x300
\n Code: e5 41 57 41 56 49 89 fe 41 55 41 54 53 48 89 f3 e8 93 b5 a3 ff 48 8d 7b 08 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 3c 02 00 0f 85 7b 02 00 00 4c 8b 63 08 31 ff 4d 89 e5 41 83 e5
\n RSP: 0018:ffff88811b15f2f0 EFLAGS: 00000202
\n RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
\n RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000000000000008
\n RBP: ffff88811b15f318 R08: 0000000000000000 R09: 0000000000000000
\n R10: 0000000000000000 R11: 0000000000000000 R12: ffff8881181eee00
\n R13: 0000000000000000 R14: ffff8881181eee00 R15: ffff8881181eee20
\n FS: 00007b1e000f76c0(0000) GS:ffff8884268e0000(0000) knlGS:0000000000000000
\n CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
\n CR2: 00007b1e00a24ac0 CR3: 0000000116eb3000 CR4: 00000000000006f0
\n Call Trace:<\/p>\n
insert_page+0x8f\/0x190
\n ? __pfx_insert_page+0x10\/0x10
\n ? kasan_save_alloc_info+0x38\/0x60
\n vm_insert_page+0x2e7\/0x400
\n remap_vmalloc_range_partial+0x212\/0x3e0
\n remap_vmalloc_range+0x6e\/0xb0
\n ? __kasan_check_write+0x14\/0x30
\n rxe_mmap+0x2e9\/0x5d0
\n ib_uverbs_mmap+0x1ad\/0x2c0
\n __mmap_region+0x12c2\/0x2ad0
\n ? __pfx___mmap_region+0x10\/0x10
\n ? __sanitizer_cov_trace_switch+0x58\/0xb0
\n ? mas_prev_slot+0x360\/0x39c0
\n ? __sanitizer_cov_trace_switch+0x58\/0xb0
\n ? mas_next_slot+0x1e5b\/0x2f40
\n ? __sanitizer_cov_trace_cmp8+0x18\/0x30
\n ? unmapped_area_topdown+0x4dd\/0x610
\n ? kfree+0x1b1\/0x440
\n ? free_cpumask_var+0x16\/0x30
\n ? __kasan_slab_free+0x7d\/0xa0
\n ? __sanitizer_cov_trace_cmp8+0x18\/0x30
\n mmap_region+0x2e6\/0x3c0
\n do_mmap+0xa3e\/0x12a0
\n ? __pfx_do_mmap+0x10\/0x10
\n ? __kasan_check_write+0x14\/0x30
\n ? down_write_killable+0xba\/0x160
\n ? __pfx_down_write_killable+0x10\/0x10
\n ? __sanitizer_cov_trace_cmp4+0x16\/0x30
\n vm_mmap_pgoff+0x2d4\/0x4a0
\n ? __pfx_vm_mmap_pgoff+0x10\/0x10
\n ? fget+0x1bf\/0x270
\n ksys_mmap_pgoff+0x40c\/0x690
\n ? __sanitizer_cov_trace_const_cmp4+0x16\/0x30
\n ? __pfx_ksys_mmap_pgoff+0x10\/0x10
\n ? __kasan_check_write+0x14\/0x30
\n ? _raw_spin_trylock+0xbb\/0x130
\n ? __pfx__raw_spin_trylock+0x10\/0x10
\n __x64_sys_mmap+0x135\/0x1e0
\n x64_sys_c
\n—truncated—<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
RDMA\/rxe: Fix a use-after-free problem in rxe_mmap<\/p>\n
rxe_mmap() removes a rxe_mmap_info struct from the pending_mmaps list
\nand relea<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-4700","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/4700","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=4700"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=4700"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=4700"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}