CVE-2024-39474: kernel: mm/vmalloc: fix vmalloc which may return null if called with __GFP_NOFAIL
Component: kernel
Severity: Low
CWE: CWE-476 (NULL Pointer Dereference)
CVSS v3: 4.7 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H)
Public date: 2024-07-05T00:00:00+00:00

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

mm/vmalloc: fix vmalloc which may return null if called with __GFP_NOFAIL

commit a421ef303008 ("mm: allow !GFP_KERNEL allocations for kvmalloc")
includes support for __GFP_NOFAIL, but it presents a conflict with commit
dd544141b9eb ("vmalloc: back off when the current task is OOM-killed").  A
possible scenario is as follows:

process-a
__vmalloc_node_range(GFP_KERNEL | __GFP_NOFAIL)
    __vmalloc_area_node()
        vm_area_alloc_pages()
		--> oom-killer send SIGKILL to process-a
        if (fatal_signal_pending(current)) break;
--> return NULL;

To fix this, do not check fatal_signal_pending() in vm_area_alloc_pages()
if __GFP_NOFAIL set.

This issue occurred during OPLUS KASAN TEST. Below is part of the log
-> oom-killer sends signal to process
[65731.222840] [ T1308] oom-kill:constraint=CONSTRAINT_NONE,nodemask=(null),cpuset=/,mems_allowed=0,global_oom,task_memcg=/apps/uid_10198,task=gs.intelligence,pid=32454,uid=10198

[65731.259685] [T32454] Call trace:
[65731.259698] [T32454]  dump_backtrace+0xf4/0x118
[65731.259734] [T32454]  show_stack+0x18/0x24
[65731.259756] [T32454]  dump_stack_lvl+0x60/0x7c
[65731.259781] [T32454]  dump_stack+0x18/0x38
[65731.259800] [T32454]  mrdump_common_die+0x250/0x39c [mrdump]
[65731.259936] [T32454]  ipanic_die+0x20/0x34 [mrdump]
[65731.260019] [T32454]  atomic_notifier_call_chain+0xb4/0xfc
[65731.260047] [T32454]  notify_die+0x114/0x198
[65731.260073] [T32454]  die+0xf4/0x5b4
[65731.260098] [T32454]  die_kernel_fault+0x80/0x98
[65731.260124] [T32454]  __do_kernel_fault+0x160/0x2a8
[65731.260146] [T32454]  do_bad_area+0x68/0x148
[65731.260174] [T32454]  do_mem_abort+0x151c/0x1b34
[65731.260204] [T32454]  el1_abort+0x3c/0x5c
[65731.260227] [T32454]  el1h_64_sync_handler+0x54/0x90
[65731.260248] [T32454]  el1h_64_sync+0x68/0x6c

[65731.260269] [T32454]  z_erofs_decompress_queue+0x7f0/0x2258
--> be->decompressed_pages = kvcalloc(be->nr_pages, sizeof(struct page *), GFP_KERNEL | __GFP_NOFAIL);
	kernel panic by NULL pointer dereference.
	erofs assume kvmalloc with __GFP_NOFAIL never return NULL.
[65731.260293] [T32454]  z_erofs_runqueue+0xf30/0x104c
[65731.260314] [T32454]  z_erofs_readahead+0x4f0/0x968
[65731.260339] [T32454]  read_pages+0x170/0xadc
[65731.260364] [T32454]  page_cache_ra_unbounded+0x874/0xf30
[65731.260388] [T32454]  page_cache_ra_order+0x24c/0x714
[65731.260411] [T32454]  filemap_fault+0xbf0/0x1a74
[65731.260437] [T32454]  __do_fault+0xd0/0x33c
[65731.260462] [T32454]  handle_mm_fault+0xf74/0x3fe0
[65731.260486] [T32454]  do_mem_abort+0x54c/0x1b34
[65731.260509] [T32454]  el0_da+0x44/0x94
[65731.260531] [T32454]  el0t_64_sync_handler+0x98/0xb4
[65731.260553] [T32454]  el0t_64_sync+0x198/0x19c


Affected upstream versions: 5.17
Fixed upstream versions: 0, 6.1.95, 6.10, 6.6.34, 6.9.5
Upstream repository: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Upstream fix commit: 198a80833e3421d4c9820a4ae907120adf598c91