| Message ID | 20241212013723.113408-1-hao.ge@linux.dev (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v4] mm/alloc_tag: Fix panic when CONFIG_KASAN enabled and CONFIG_KASAN_VMALLOC not enabled | expand |
On Wed, Dec 11, 2024 at 5:38 PM Hao Ge <hao.ge@linux.dev> wrote: > > From: Hao Ge <gehao@kylinos.cn> > > When CONFIG_KASAN is enabled but CONFIG_KASAN_VMALLOC > is not enabled, we may encounter a panic during system boot. > > Because we haven't allocated pages and created mappings > for the shadow memory corresponding to module_tags region, > similar to how it is done for execmem_vmalloc. > > The difference is that our module_tags are allocated on demand, > so similarly,we also need to allocate shadow memory regions on demand. > However, we still need to adhere to the MODULE_ALIGN principle. nit: the above wording is a bit unclear. Instead of module_tags I would call it "memory for module allocation tags". So, I would change the above paragraph to: The memory for module allocation tags is allocated on demand, therefore we need to allocate shadow memory on demand as well in MODULE_ALIGN blocks. > > Here is the log for panic: > > [ 18.349421] BUG: unable to handle page fault for address: fffffbfff8092000 > [ 18.350016] #PF: supervisor read access in kernel mode > [ 18.350459] #PF: error_code(0x0000) - not-present page > [ 18.350904] PGD 20fe52067 P4D 219dc8067 PUD 219dc4067 PMD 102495067 PTE 0 > [ 18.351484] Oops: Oops: 0000 [#1] PREEMPT SMP KASAN NOPTI > [ 18.351961] CPU: 5 UID: 0 PID: 1 Comm: systemd Not tainted 6.13.0-rc1+ #3 > [ 18.352533] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 > [ 18.353494] RIP: 0010:kasan_check_range+0xba/0x1b0 > [ 18.353931] Code: 8d 5a 07 4c 0f 49 da 49 c1 fb 03 45 85 db 0f 84 dd 00 00 00 45 89 db 4a 8d 14 d8 eb 0d 48 83 c0 08 48 39 c2 0f 84 c1 00 00 00 <48> 83 38 00 74 ed 48 8d 50 08 eb 0d 48 83 c0 01 48 39 d0 0f 84 90 > [ 18.355484] RSP: 0018:ff11000101877958 EFLAGS: 00010206 > [ 18.355937] RAX: fffffbfff8092000 RBX: fffffbfff809201e RCX: ffffffff82a7ceac > [ 18.356542] RDX: fffffbfff8092018 RSI: 00000000000000f0 RDI: ffffffffc0490000 > [ 18.357153] RBP: fffffbfff8092000 R08: 0000000000000001 R09: fffffbfff809201d > [ 18.357756] R10: ffffffffc04900ef R11: 0000000000000003 R12: ffffffffc0490000 > [ 18.358365] R13: ff11000101877b48 R14: ffffffffc0490000 R15: 000000000000002c > [ 18.358968] FS: 00007f9bd13c5940(0000) GS:ff110001eb480000(0000) knlGS:0000000000000000 > [ 18.359648] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 18.360178] CR2: fffffbfff8092000 CR3: 0000000109214004 CR4: 0000000000771ef0 > [ 18.360790] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 18.361404] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > [ 18.362020] PKRU: 55555554 > [ 18.362261] Call Trace: > [ 18.362481] <TASK> > [ 18.362671] ? __die+0x23/0x70 > [ 18.362964] ? page_fault_oops+0xc2/0x160 > [ 18.363318] ? exc_page_fault+0xad/0xc0 > [ 18.363680] ? asm_exc_page_fault+0x26/0x30 > [ 18.364056] ? move_module+0x3cc/0x8a0 > [ 18.364398] ? kasan_check_range+0xba/0x1b0 > [ 18.364755] __asan_memcpy+0x3c/0x60 > [ 18.365074] move_module+0x3cc/0x8a0 > [ 18.365386] layout_and_allocate.constprop.0+0x3d5/0x720 > [ 18.365841] ? early_mod_check+0x3dc/0x510 > [ 18.366195] load_module+0x72/0x1850 > [ 18.366509] ? __pfx_kernel_read_file+0x10/0x10 > [ 18.366918] ? vm_mmap_pgoff+0x21c/0x2d0 > [ 18.367262] init_module_from_file+0xd1/0x130 > [ 18.367638] ? __pfx_init_module_from_file+0x10/0x10 > [ 18.368073] ? __pfx__raw_spin_lock+0x10/0x10 > [ 18.368456] ? __pfx_cred_has_capability.isra.0+0x10/0x10 > [ 18.368938] idempotent_init_module+0x22c/0x790 > [ 18.369332] ? simple_getattr+0x6f/0x120 > [ 18.369676] ? __pfx_idempotent_init_module+0x10/0x10 > [ 18.370110] ? fdget+0x58/0x3a0 > [ 18.370393] ? security_capable+0x64/0xf0 > [ 18.370745] __x64_sys_finit_module+0xc2/0x140 > [ 18.371136] do_syscall_64+0x7d/0x160 > [ 18.371459] ? fdget_pos+0x1c8/0x4c0 > [ 18.371784] ? ksys_read+0xfd/0x1d0 > [ 18.372106] ? syscall_exit_to_user_mode+0x10/0x1f0 > [ 18.372525] ? do_syscall_64+0x89/0x160 > [ 18.372860] ? do_syscall_64+0x89/0x160 > [ 18.373194] ? do_syscall_64+0x89/0x160 > [ 18.373527] ? syscall_exit_to_user_mode+0x10/0x1f0 > [ 18.373952] ? do_syscall_64+0x89/0x160 > [ 18.374283] ? syscall_exit_to_user_mode+0x10/0x1f0 > [ 18.374701] ? do_syscall_64+0x89/0x160 > [ 18.375037] ? do_user_addr_fault+0x4a8/0xa40 > [ 18.375416] ? clear_bhb_loop+0x25/0x80 > [ 18.375748] ? clear_bhb_loop+0x25/0x80 > [ 18.376119] ? clear_bhb_loop+0x25/0x80 > [ 18.376450] entry_SYSCALL_64_after_hwframe+0x76/0x7e > > Fixes: 233e89322cbe ("alloc_tag: fix module allocation tags populated area calculation") > Reported-by: Ben Greear <greearb@candelatech.com> > Closes: https://lore.kernel.org/all/1ba0cc57-e2ed-caa2-1241-aa5615bee01f@candelatech.com/ > Suggested-by: Suren Baghdasaryan <surenb@google.com> > Signed-off-by: Hao Ge <gehao@kylinos.cn> Other than that nit, LGTM. Acked-by: Suren Baghdasaryan <surenb@google.com> > --- > v4: Based on Suren's suggestion for modification (to make the code simpler), > modify the code. > Update the comments in the code due to the modifications made to the code. > Add Suggested-by: Suren Baghdasaryan <surenb@google.com> > > v3: Adjusting the title because the previous one was a bit unclear. > Suren has pointed out that our condition for determining whether > to allocate shadow memory is unreasonable.We have adjusted our method > to use every 8 pages as an index (idx), and we will make decisions based > on this idx when determining whether to allocate shadow memory. > > v2: Add comments to facilitate understanding of the code. > Add align nr << PAGE_SHIFT to MODULE_ALIGN,even though kasan_alloc_module_shadow > already handles this internally,but to make the code more readable and user-friendly > > commit 233e89322cbe ("alloc_tag: fix module allocation > tags populated area calculation") is currently in the > mm-hotfixes-unstable branch, so this patch is > developed based on the mm-hotfixes-unstable branch. > --- > lib/alloc_tag.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c > index f942408b53ef..c5bdfa297a35 100644 > --- a/lib/alloc_tag.c > +++ b/lib/alloc_tag.c > @@ -407,6 +407,8 @@ static int vm_module_tags_populate(void) > > if (phys_end < new_end) { > struct page **next_page = vm_module_tags->pages + vm_module_tags->nr_pages; > + unsigned long old_shadow_end = ALIGN(phys_end, MODULE_ALIGN); > + unsigned long new_shadow_end = ALIGN(new_end, MODULE_ALIGN); > unsigned long more_pages; > unsigned long nr; > > @@ -421,7 +423,19 @@ static int vm_module_tags_populate(void) > __free_page(next_page[i]); > return -ENOMEM; > } > + > vm_module_tags->nr_pages += nr; > + > + /* > + * Kasan allocates 1 byte of shadow for every 8 bytes of data. > + * When kasan_alloc_module_shadow allocates shadow memory, > + * its unit of allocation is a page. > + * Therefore, here we need to align to MODULE_ALIGN. > + */ > + if (old_shadow_end < new_shadow_end) > + kasan_alloc_module_shadow((void *)old_shadow_end, > + new_shadow_end - old_shadow_end, > + GFP_KERNEL); > } > > /* > -- > 2.25.1 >
diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c index f942408b53ef..c5bdfa297a35 100644 --- a/lib/alloc_tag.c +++ b/lib/alloc_tag.c @@ -407,6 +407,8 @@ static int vm_module_tags_populate(void) if (phys_end < new_end) { struct page **next_page = vm_module_tags->pages + vm_module_tags->nr_pages; + unsigned long old_shadow_end = ALIGN(phys_end, MODULE_ALIGN); + unsigned long new_shadow_end = ALIGN(new_end, MODULE_ALIGN); unsigned long more_pages; unsigned long nr; @@ -421,7 +423,19 @@ static int vm_module_tags_populate(void) __free_page(next_page[i]); return -ENOMEM; } + vm_module_tags->nr_pages += nr; + + /* + * Kasan allocates 1 byte of shadow for every 8 bytes of data. + * When kasan_alloc_module_shadow allocates shadow memory, + * its unit of allocation is a page. + * Therefore, here we need to align to MODULE_ALIGN. + */ + if (old_shadow_end < new_shadow_end) + kasan_alloc_module_shadow((void *)old_shadow_end, + new_shadow_end - old_shadow_end, + GFP_KERNEL); } /*