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authorLaura Abbott <labbott@redhat.com>2018-05-12 02:01:57 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2018-05-12 03:28:45 +0300
commit3955333df9a50e8783d115613a397ae55d905080 (patch)
tree371edec8aa4acd6f21c17c32efd5f526bce5ee85
parent7aaf7727235870f497eb928f728f7773d6df3b40 (diff)
downloadlinux-sunxi-3955333df9a50e8783d115613a397ae55d905080.tar.xz
proc/kcore: don't bounds check against address 0
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.com>a Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/proc/kcore.c23
1 files changed, 16 insertions, 7 deletions
diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index d1e82761de81..e64ecb9f2720 100644
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -209,25 +209,34 @@ kclist_add_private(unsigned long pfn, unsigned long nr_pages, void *arg)
{
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;
}