From: Yongqiang Liu liuyongqiang13@huawei.com

mainline inclusion from mainline-v6.9-rc1 commit 0c66c6f4e21cb22220cbd8821c5c73fc157d20dc category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9L5E2 CVE: CVE-2024-26947

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

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Since commit a4d5613c4dc6 ("arm: extend pfn_valid to take into account freed memory map alignment") changes the semantics of pfn_valid() to check presence of the memory map for a PFN. A valid page for an address which is reserved but not mapped by the kernel[1], the system crashed during some uio test with the following memory layout:

node 0: [mem 0x00000000c0a00000-0x00000000cc8fffff] node 0: [mem 0x00000000d0000000-0x00000000da1fffff] the uio layout is：0xc0900000, 0x100000

the crash backtrace like:

Unable to handle kernel paging request at virtual address bff00000 [...] CPU: 1 PID: 465 Comm: startapp.bin Tainted: G O 5.10.0 #1 Hardware name: Generic DT based system PC is at b15_flush_kern_dcache_area+0x24/0x3c LR is at __sync_icache_dcache+0x6c/0x98 [...] (b15_flush_kern_dcache_area) from (__sync_icache_dcache+0x6c/0x98) (__sync_icache_dcache) from (set_pte_at+0x28/0x54) (set_pte_at) from (remap_pfn_range+0x1a0/0x274) (remap_pfn_range) from (uio_mmap+0x184/0x1b8 [uio]) (uio_mmap [uio]) from (__mmap_region+0x264/0x5f4) (__mmap_region) from (__do_mmap_mm+0x3ec/0x440) (__do_mmap_mm) from (do_mmap+0x50/0x58) (do_mmap) from (vm_mmap_pgoff+0xfc/0x188) (vm_mmap_pgoff) from (ksys_mmap_pgoff+0xac/0xc4) (ksys_mmap_pgoff) from (ret_fast_syscall+0x0/0x5c) Code: e0801001 e2423001 e1c00003 f57ff04f (ee070f3e) ---[ end trace 09cf0734c3805d52 ]--- Kernel panic - not syncing: Fatal exception

So check if PG_reserved was set to solve this issue.

[1]: https://lore.kernel.org/lkml/Zbtdue57RO0QScJM@linux.ibm.com/

Fixes: a4d5613c4dc6 ("arm: extend pfn_valid to take into account freed memory map alignment") Suggested-by: Mike Rapoport rppt@linux.ibm.com Signed-off-by: Yongqiang Liu liuyongqiang13@huawei.com Signed-off-by: Russell King (Oracle) rmk+kernel@armlinux.org.uk

Conflicts: arch/arm/mm/flush.c [Conflicts due to folio api.] Signed-off-by: Jinjiang Tu tujinjiang@huawei.com --- arch/arm/mm/flush.c | 3 +++ 1 file changed, 3 insertions(+)

diff --git a/arch/arm/mm/flush.c b/arch/arm/mm/flush.c index 6d89db7895d1..ef848bf0df28 100644 --- a/arch/arm/mm/flush.c +++ b/arch/arm/mm/flush.c @@ -280,6 +280,9 @@ void __sync_icache_dcache(pte_t pteval) return;

page = pfn_to_page(pfn); + if (PageReserved(page)) + return; + if (cache_is_vipt_aliasing()) mapping = page_mapping_file(page); else