4.16-stable review patch. If anyone has any objections, please let me know.
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From: Laura Abbott labbott@redhat.com
[ Upstream commit 3955333df9a50e8783d115613a397ae55d905080 ]
The existing kcore code checks for bad addresses against __va(0) with the assumption that this is the lowest address on the system. This may not hold true on some systems (e.g. arm64) and produce overflows and crashes. Switch to using other functions to validate the address range.
It's currently only seen on arm64 and it's not clear if anyone wants to use that particular combination on a stable release. So this is not urgent for stable.
Link: http://lkml.kernel.org/r/20180501201143.15121-1-labbott@redhat.com Signed-off-by: Laura Abbott labbott@redhat.com Tested-by: Dave Anderson anderson@redhat.com Cc: Kees Cook keescook@chromium.org Cc: Ard Biesheuvel ard.biesheuvel@linaro.org Cc: Ingo Molnar mingo@kernel.org Cc: Andi Kleen andi@firstfloor.org Cc: Alexey Dobriyan adobriyan@gmail.coma Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/proc/kcore.c | 23 ++++++++++++++++------- 1 file changed, 16 insertions(+), 7 deletions(-)
--- a/fs/proc/kcore.c +++ b/fs/proc/kcore.c @@ -209,25 +209,34 @@ kclist_add_private(unsigned long pfn, un { struct list_head *head = (struct list_head *)arg; struct kcore_list *ent; + struct page *p; + + if (!pfn_valid(pfn)) + return 1; + + p = pfn_to_page(pfn); + if (!memmap_valid_within(pfn, p, page_zone(p))) + return 1;
ent = kmalloc(sizeof(*ent), GFP_KERNEL); if (!ent) return -ENOMEM; - ent->addr = (unsigned long)__va((pfn << PAGE_SHIFT)); + ent->addr = (unsigned long)page_to_virt(p); ent->size = nr_pages << PAGE_SHIFT;
- /* Sanity check: Can happen in 32bit arch...maybe */ - if (ent->addr < (unsigned long) __va(0)) + if (!virt_addr_valid(ent->addr)) goto free_out;
/* cut not-mapped area. ....from ppc-32 code. */ if (ULONG_MAX - ent->addr < ent->size) ent->size = ULONG_MAX - ent->addr;
- /* cut when vmalloc() area is higher than direct-map area */ - if (VMALLOC_START > (unsigned long)__va(0)) { - if (ent->addr > VMALLOC_START) - goto free_out; + /* + * We've already checked virt_addr_valid so we know this address + * is a valid pointer, therefore we can check against it to determine + * if we need to trim + */ + if (VMALLOC_START > ent->addr) { if (VMALLOC_START - ent->addr < ent->size) ent->size = VMALLOC_START - ent->addr; }