mirror of
https://github.com/Fishwaldo/Star64_linux.git
synced 2025-03-16 04:04:06 +00:00
arm64: mte: Avoid setting PG_mte_tagged if no tags cleared or restored
[ Upstream commita8e5e5146a
] Prior to commit69e3b846d8
("arm64: mte: Sync tags for pages where PTE is untagged"), mte_sync_tags() was only called for pte_tagged() entries (those mapped with PROT_MTE). Therefore mte_sync_tags() could safely use test_and_set_bit(PG_mte_tagged, &page->flags) without inadvertently setting PG_mte_tagged on an untagged page. The above commit was required as guests may enable MTE without any control at the stage 2 mapping, nor a PROT_MTE mapping in the VMM. However, the side-effect was that any page with a PTE that looked like swap (or migration) was getting PG_mte_tagged set automatically. A subsequent page copy (e.g. migration) copied the tags to the destination page even if the tags were owned by KASAN. This issue was masked by the page_kasan_tag_reset() call introduced in commite5b8d92189
("arm64: mte: reset the page tag in page->flags"). When this commit was reverted (20794545c1
), KASAN started reporting access faults because the overriding tags in a page did not match the original page->flags (with CONFIG_KASAN_HW_TAGS=y): BUG: KASAN: invalid-access in copy_page+0x10/0xd0 arch/arm64/lib/copy_page.S:26 Read at addr f5ff000017f2e000 by task syz-executor.1/2218 Pointer tag: [f5], memory tag: [f2] Move the PG_mte_tagged bit setting from mte_sync_tags() to the actual place where tags are cleared (mte_sync_page_tags()) or restored (mte_restore_tags()). Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Reported-by: syzbot+c2c79c6d6eddc5262b77@syzkaller.appspotmail.com Fixes:69e3b846d8
("arm64: mte: Sync tags for pages where PTE is untagged") Cc: <stable@vger.kernel.org> # 5.14.x Cc: Steven Price <steven.price@arm.com> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/0000000000004387dc05e5888ae5@google.com/ Reviewed-by: Steven Price <steven.price@arm.com> Link: https://lore.kernel.org/r/20221006163354.3194102-1-catalin.marinas@arm.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
parent
831f24e715
commit
8186edef51
2 changed files with 13 additions and 3 deletions
|
@ -53,7 +53,12 @@ static void mte_sync_page_tags(struct page *page, pte_t old_pte,
|
|||
* the new page->flags are visible before the tags were updated.
|
||||
*/
|
||||
smp_wmb();
|
||||
mte_clear_page_tags(page_address(page));
|
||||
/*
|
||||
* Test PG_mte_tagged again in case it was racing with another
|
||||
* set_pte_at().
|
||||
*/
|
||||
if (!test_and_set_bit(PG_mte_tagged, &page->flags))
|
||||
mte_clear_page_tags(page_address(page));
|
||||
}
|
||||
|
||||
void mte_sync_tags(pte_t old_pte, pte_t pte)
|
||||
|
@ -69,7 +74,7 @@ void mte_sync_tags(pte_t old_pte, pte_t pte)
|
|||
|
||||
/* if PG_mte_tagged is set, tags have already been initialised */
|
||||
for (i = 0; i < nr_pages; i++, page++) {
|
||||
if (!test_and_set_bit(PG_mte_tagged, &page->flags))
|
||||
if (!test_bit(PG_mte_tagged, &page->flags))
|
||||
mte_sync_page_tags(page, old_pte, check_swap,
|
||||
pte_is_tagged);
|
||||
}
|
||||
|
|
|
@ -62,7 +62,12 @@ bool mte_restore_tags(swp_entry_t entry, struct page *page)
|
|||
* the new page->flags are visible before the tags were updated.
|
||||
*/
|
||||
smp_wmb();
|
||||
mte_restore_page_tags(page_address(page), tags);
|
||||
/*
|
||||
* Test PG_mte_tagged again in case it was racing with another
|
||||
* set_pte_at().
|
||||
*/
|
||||
if (!test_and_set_bit(PG_mte_tagged, &page->flags))
|
||||
mte_restore_page_tags(page_address(page), tags);
|
||||
|
||||
return true;
|
||||
}
|
||||
|
|
Loading…
Add table
Reference in a new issue