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authorMichael Hennerich <Michael.Hennerich@analog.com>2008-04-28 02:13:38 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-28 08:58:26 -0700
commit4016a1390d07f15b267eecb20e76a48fd5c524ef (patch)
treeae9ce9bd7d2fd784a396893c4d4b2a79b2d7342d /security/commoncap.c
parent468fd62ed9090ccbe872489df5d0d099510df4b5 (diff)
downloadlinux-4016a1390d07f15b267eecb20e76a48fd5c524ef.tar.gz
mm/nommu.c: return 0 from kobjsize with invalid objects
Don't perform kobjsize operations on objects the kernel doesn't manage. On Blackfin, drivers can get dma coherent memory by calling a function dma_alloc_coherent(). We do this in nommu by configuring a chunk of uncached memory at the top of memory. Since we don't want the kernel to use the uncached memory, we lie to the kernel, and tell it that it's max memory is between 0, and the start of the uncached dma coherent section. this all works well, until this memory gets exposed into userspace (with a frame buffer), when you look at the process's maps, it shows the framebuf: root:/proc> cat maps [snip] 03f0ef00-03f34700 rw-p 00000000 1f:00 192 /dev/fb0 root:/proc> This is outside the "normal" range for the kernel. When the kernel tries to find the size of this object (when you run ps), it dies in nommu.c in kobjsize. BUG_ON(page->index >= MAX_ORDER); since the page we are referring to is outside what the kernel thinks is it's max valid memory. root:~> while [ 1 ]; ps > /dev/null; done kernel BUG at mm/nommu.c:119! Kernel panic - not syncing: BUG! We fixed this by adding a check to reject out of range object pointers as it already does that for NULL pointers. Signed-off-by: Michael Hennerich <Michael.Hennerich@analog.com> Signed-off-by: Robin Getz <rgetz@blackfin.uclinux.org> Acked-by: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'security/commoncap.c')
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