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Mainline Linux tree for various devices, only for fun :)
4fcdcc1291
vmap() takes struct page *pages as one of arguments, and user may provide an invalid pointer which may lead to corrupted translation table. An example of such behaviour is erroneous usage of virt_to_page(): vaddr1 = dma_alloc_coherent() page = virt_to_page() // Wrong here ... vaddr2 = vmap(page) memset(vaddr2) // Faulting here virt_to_page() returns a wrong pointer if vaddr1 is not a linear kernel address. The problem is that vmap() populates pte with bad pfn successfully, and it's much harder to debug at memory access time. This case should be caught by DEBUG_VIRTUAL being that enabled, but it's not enabled in popular distros. Kernel already checks the pages against NULL. In the case mentioned above, however, the address is not NULL, and it's big enough so that the hardware generated Address Size Abort on arm64: [ 665.484101] Unhandled fault at 0xffff8000252cd000 [ 665.488807] Mem abort info: [ 665.491617] ESR = 0x96000043 [ 665.494675] EC = 0x25: DABT (current EL), IL = 32 bits [ 665.499985] SET = 0, FnV = 0 [ 665.503039] EA = 0, S1PTW = 0 [ 665.506167] Data abort info: [ 665.509047] ISV = 0, ISS = 0x00000043 [ 665.512882] CM = 0, WnR = 1 [ 665.515851] swapper pgtable: 4k pages, 48-bit VAs, pgdp=00000000818cb000 [ 665.522550] [ffff8000252cd000] pgd=000000affcfff003, pud=000000affcffe003, pmd=0000008fad8c3003, pte=00688000a5217713 [ 665.533160] Internal error: level 3 address size fault: 96000043 [#1] SMP [ 665.539936] Modules linked in: [...] [ 665.616212] CPU: 178 PID: 13199 Comm: test Tainted: P OE 5.4.0-84-generic #94~18.04.1-Ubuntu [ 665.626806] Hardware name: HPE Apollo 70 /C01_APACHE_MB , BIOS L50_5.13_1.0.6 07/10/2018 [ 665.636618] pstate: 80400009 (Nzcv daif +PAN -UAO) [ 665.641407] pc : __memset+0x38/0x188 [ 665.645146] lr : test+0xcc/0x3f8 [ 665.650184] sp : ffff8000359bb840 [ 665.653486] x29: ffff8000359bb840 x28: 0000000000000000 [ 665.658785] x27: 0000000000000000 x26: 0000000000231000 [ 665.664083] x25: ffff00ae660f6110 x24: ffff00ae668cb800 [ 665.669382] x23: 0000000000000001 x22: ffff00af533e5000 [ 665.674680] x21: 0000000000001000 x20: 0000000000000000 [ 665.679978] x19: ffff00ae66950000 x18: ffffffffffffffff [ 665.685276] x17: 00000000588636a5 x16: 0000000000000013 [ 665.690574] x15: ffffffffffffffff x14: 000000000007ffff [ 665.695872] x13: 0000000080000000 x12: 0140000000000000 [ 665.701170] x11: 0000000000000041 x10: ffff8000652cd000 [ 665.706468] x9 : ffff8000252cf000 x8 : ffff8000252cd000 [ 665.711767] x7 : 0303030303030303 x6 : 0000000000001000 [ 665.717065] x5 : ffff8000252cd000 x4 : 0000000000000000 [ 665.722363] x3 : ffff8000252cdfff x2 : 0000000000000001 [ 665.727661] x1 : 0000000000000003 x0 : ffff8000252cd000 [ 665.732960] Call trace: [ 665.735395] __memset+0x38/0x188 [...] Interestingly, this abort happens even if copy_from_kernel_nofault() is used, which is quite inconvenient for debugging purposes. This patch adds a pfn_valid() check into vmap() path, so that invalid mapping will not be created; WARN_ON() is used to let client code know that something goes wrong, and it's not a regular EINVAL situation. Link: https://lkml.kernel.org/r/20220422220410.1308706-1-yury.norov@gmail.com Signed-off-by: Yury Norov (NVIDIA) <yury.norov@gmail.com> Suggested-by: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Alexey Klimov <aklimov@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Ding Tianhong <dingtianhong@huawei.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Robin Murphy <robin.murphy@arm.com> Cc: Russell King <linux@armlinux.org.uk> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
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| kernel | ||
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| mm | ||
| net | ||
| samples | ||
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| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
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| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.