arm[64]/memremap: don't abuse pfn_valid() to ensure presence of linear map

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@sirena.org.uk
Link: https://lkml.kernel.org/r/20220426060107.7618-1-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Reported-by: "kernelci.org bot" <bot@kernelci.org>
Tested-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Will Deacon <will@kernel.org>
Cc: <stable@vger.kernel.org>	[5.4+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h
index 0c70eb688a00cb82484e2f474fcfa0e1ca796ce6..2a0739a2350bef8e2590f7b2d7464e9d60717568 100644 (file)
--- a/arch/arm/include/asm/io.h
+++ b/arch/arm/include/asm/io.h
@@ -440,6 +440,9 @@ extern void pci_iounmap(struct pci_dev *dev, void __iomem *addr);
 #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
 
 /*

diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c
index aa08bcb72db935f6e0b8012366936472ab08b10e..290702328a33704f1f1ee552b599231a2c58f122 100644 (file)
--- a/arch/arm/mm/ioremap.c
+++ b/arch/arm/mm/ioremap.c
@@ -493,3 +493,11 @@ 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);
+}

diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h
index 7fd836bea7eb42853883fae3ea5015867e3dd0b9..3995652daf81a0af14bba4da469fcfa4a633887d 100644 (file)
--- a/arch/arm64/include/asm/io.h
+++ b/arch/arm64/include/asm/io.h
@@ -192,4 +192,8 @@ extern void __iomem *ioremap_cache(phys_addr_t phys_addr, size_t size);
 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 */

diff --git a/arch/arm64/mm/ioremap.c b/arch/arm64/mm/ioremap.c
index b7c81dacabf079f50d6d6225a43b15a2b4e621ab..b21f91cd830db4fdbcf4f52f2477c3c96a875e0f 100644 (file)
--- 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);
+}