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| author | Vitaly Kuznetsov <vkuznets@redhat.com> | 2016-05-31 11:23:43 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-06-03 09:57:35 +0200 |
| commit | 55f1ea15216a5a14c96738bd5284100a00ffa9dc (patch) | |
| tree | d3632db3b2815f0cdf1c96877d64d27151dc2206 | |
| parent | 4340fa55298d17049e71c7a34e04647379c269f3 (diff) | |
| download | linux-55f1ea15216a5a14c96738bd5284100a00ffa9dc.tar.bz2 | |
efi: Fix for_each_efi_memory_desc_in_map() for empty memmaps
Commit:
78ce248faa3c ("efi: Iterate over efi.memmap in for_each_efi_memory_desc()")
introduced a regression for systems booted with the 'noefi' kernel option.
In particular, I observed an early kernel hang in efi_find_mirror()'s
for_each_efi_memory_desc() call. As we don't have efi memmap on this
system we enter this iterator with the following parameters:
efi.memmap.map = 0, efi.memmap.map_end = 0, efi.memmap.desc_size = 28
... then for_each_efi_memory_desc_in_map() does the following comparison:
(md) <= (efi_memory_desc_t *)((m)->map_end - (m)->desc_size);
... where md = 0, (m)->map_end = 0 and (m)->desc_size = 28 but when we subtract
something from a NULL pointer wrap around happens and we end up returning
invalid pointer and crash.
Fix it by using the correct pointer arithmetics.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Salter <msalter@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Fixes: 78ce248faa3c ("efi: Iterate over efi.memmap in for_each_efi_memory_desc()")
Link: http://lkml.kernel.org/r/1464690224-4503-2-git-send-email-matt@codeblueprint.co.uk
[ Made the changelog more readable. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | include/linux/efi.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/efi.h b/include/linux/efi.h index c2db3ca22217..f196dd0b0f2f 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -1005,7 +1005,7 @@ extern int efi_memattr_apply_permissions(struct mm_struct *mm, /* Iterate through an efi_memory_map */ #define for_each_efi_memory_desc_in_map(m, md) \ for ((md) = (m)->map; \ - (md) <= (efi_memory_desc_t *)((m)->map_end - (m)->desc_size); \ + ((void *)(md) + (m)->desc_size) <= (m)->map_end; \ (md) = (void *)(md) + (m)->desc_size) /** |