On 12-10-30 03:00 PM, Theodore Ts'o wrote:
On Tue, Oct 30, 2012 at 02:40:04PM -0400, Behan Webster wrote:
From: Mark Charlebois <charlebm@xxxxxxxxx>
The use of variable length arrays in structs (VLAIS) in the Linux Kernel code
precludes the use of compilers which don't implement VLAIS (for instance the
Clang compiler). Since ctx is always a 32-bit CRC, hard coding a size of 4
bytes accomplishes the same thing without the use of VLAIS. This is the same
technique already employed in fs/ext4/ext4.h
Signed-off-by: Mark Charlebois <charlebm@xxxxxxxxx>
Signed-off-by: Behan Webster <behanw@xxxxxxxxxxxxxxxxxx>
That's reasonable, but in order to be safe to make sure we don't
accidentally introduce a stack overrun bug at some point in the
future, we should do something like this instead
+ #define JBD_MAX_CHECKSUM_SIZE 4
.
.
.
- char ctx[crypto_shash_descsize(journal->j_chksum_driver)];
+ char ctx[JBD_MAX_CHECKSUM_SIZE];
.
.
.
+ BUG_ON(crypto_shash_descsize(journal->j_chksum_driver) >
+ JBD_MAX_CHECKSUM_SIZE);
I just like being careful and paranoid; using magic numeric constants
for buffer sizes is just a scary thing to do. If you could resubmit
the patch with this change, I'd really appreciate it. Thanks!!
A very good idea. Will do. Expect it soon.
Behan
--
Behan Webster
behanw@xxxxxxxxxxxxxxxxxx
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