This is a note to let you know that I've just added the patch titled arm[64]/memremap: don't abuse pfn_valid() to ensure presence of linear map to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: arm-memremap-don-t-abuse-pfn_valid-to-ensure-presence-of-linear-map.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 260364d112bc822005224667c0c9b1b17a53eafd Mon Sep 17 00:00:00 2001 From: Mike Rapoport <rppt@xxxxxxxxxxxxx> Date: Mon, 9 May 2022 17:34:28 -0700 Subject: arm[64]/memremap: don't abuse pfn_valid() to ensure presence of linear map From: Mike Rapoport <rppt@xxxxxxxxxxxxx> commit 260364d112bc822005224667c0c9b1b17a53eafd upstream. The semantics of pfn_valid() is to check presence of the memory map for a PFN and not whether a PFN is covered by the linear map. The memory map may be present for NOMAP memory regions, but they won't be mapped in the linear mapping. Accessing such regions via __va() when they are memremap()'ed will cause a crash. On v5.4.y the crash happens on qemu-arm with UEFI [1]: <1>[ 0.084476] 8<--- cut here --- <1>[ 0.084595] Unable to handle kernel paging request at virtual address dfb76000 <1>[ 0.084938] pgd = (ptrval) <1>[ 0.085038] [dfb76000] *pgd=5f7fe801, *pte=00000000, *ppte=00000000 ... <4>[ 0.093923] [<c0ed6ce8>] (memcpy) from [<c16a06f8>] (dmi_setup+0x60/0x418) <4>[ 0.094204] [<c16a06f8>] (dmi_setup) from [<c16a38d4>] (arm_dmi_init+0x8/0x10) <4>[ 0.094408] [<c16a38d4>] (arm_dmi_init) from [<c0302e9c>] (do_one_initcall+0x50/0x228) <4>[ 0.094619] [<c0302e9c>] (do_one_initcall) from [<c16011e4>] (kernel_init_freeable+0x15c/0x1f8) <4>[ 0.094841] [<c16011e4>] (kernel_init_freeable) from [<c0f028cc>] (kernel_init+0x8/0x10c) <4>[ 0.095057] [<c0f028cc>] (kernel_init) from [<c03010e8>] (ret_from_fork+0x14/0x2c) On kernels v5.10.y and newer the same crash won't reproduce on ARM because commit b10d6bca8720 ("arch, drivers: replace for_each_membock() with for_each_mem_range()") changed the way memory regions are registered in the resource tree, but that merely covers up the problem. On ARM64 memory resources registered in yet another way and there the issue of wrong usage of pfn_valid() to ensure availability of the linear map is also covered. Implement arch_memremap_can_ram_remap() on ARM and ARM64 to prevent access to NOMAP regions via the linear mapping in memremap(). Link: https://lore.kernel.org/all/Yl65zxGgFzF1Okac@xxxxxxxxxxxxx Link: https://lkml.kernel.org/r/20220426060107.7618-1-rppt@xxxxxxxxxx Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx> Reported-by: "kernelci.org bot" <bot@xxxxxxxxxxxx> Tested-by: Mark Brown <broonie@xxxxxxxxxx> Reviewed-by: Ard Biesheuvel <ardb@xxxxxxxxxx> Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: Mark Brown <broonie@xxxxxxxxxx> Cc: Mark-PK Tsai <mark-pk.tsai@xxxxxxxxxxxx> Cc: Russell King <linux@xxxxxxxxxxxxxxx> Cc: Tony Lindgren <tony@xxxxxxxxxxx> Cc: Will Deacon <will@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> [5.4+] Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/arm/include/asm/io.h | 3 +++ arch/arm/mm/ioremap.c | 8 ++++++++ arch/arm64/include/asm/io.h | 4 ++++ arch/arm64/mm/ioremap.c | 8 ++++++++ 4 files changed, 23 insertions(+) --- a/arch/arm/include/asm/io.h +++ b/arch/arm/include/asm/io.h @@ -436,6 +436,9 @@ extern void pci_iounmap(struct pci_dev * #define ARCH_HAS_VALID_PHYS_ADDR_RANGE extern int valid_phys_addr_range(phys_addr_t addr, size_t size); extern int valid_mmap_phys_addr_range(unsigned long pfn, size_t size); +extern bool arch_memremap_can_ram_remap(resource_size_t offset, size_t size, + unsigned long flags); +#define arch_memremap_can_ram_remap arch_memremap_can_ram_remap #endif /* --- a/arch/arm/mm/ioremap.c +++ b/arch/arm/mm/ioremap.c @@ -479,3 +479,11 @@ void __init early_ioremap_init(void) { early_ioremap_setup(); } + +bool arch_memremap_can_ram_remap(resource_size_t offset, size_t size, + unsigned long flags) +{ + unsigned long pfn = PHYS_PFN(offset); + + return memblock_is_map_memory(pfn); +} --- a/arch/arm64/include/asm/io.h +++ b/arch/arm64/include/asm/io.h @@ -192,4 +192,8 @@ extern void __iomem *ioremap_cache(phys_ extern int valid_phys_addr_range(phys_addr_t addr, size_t size); extern int valid_mmap_phys_addr_range(unsigned long pfn, size_t size); +extern bool arch_memremap_can_ram_remap(resource_size_t offset, size_t size, + unsigned long flags); +#define arch_memremap_can_ram_remap arch_memremap_can_ram_remap + #endif /* __ASM_IO_H */ --- a/arch/arm64/mm/ioremap.c +++ b/arch/arm64/mm/ioremap.c @@ -99,3 +99,11 @@ void __init early_ioremap_init(void) { early_ioremap_setup(); } + +bool arch_memremap_can_ram_remap(resource_size_t offset, size_t size, + unsigned long flags) +{ + unsigned long pfn = PHYS_PFN(offset); + + return pfn_is_map_memory(pfn); +} Patches currently in stable-queue which might be from rppt@xxxxxxxxxxxxx are queue-5.15/arm-memremap-don-t-abuse-pfn_valid-to-ensure-presence-of-linear-map.patch