[Qemu-devel] Segementation fault running qemu-img commit

[Ryan Rempel]

I was getting a segmentation fault when running "qemu-img commit" (to
commit changes back to the underlying filesystem).

It appears that the problem is that there is code in block-cow.c that
"reads ahead" in a bitmap without checking whether it is falling off
the end of the bitmap. At least in my case (running on FreeBSD 5) this
ends up causing a segmentation fault.

I've attached a patch which appears to fix the problem (I'm not sure
if it is the most elegant fix). I've tried to avoid an "off-by-one"
problem in the patch, but you should probably review it to make sure
I've got the logic right.

patch-block-cow.c
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