Jan Engelhardt schreef:
Patrick McHardy wrote on 2009-06-02 12:20:45:
Jan Engelhardt wrote:
Since the kernel uses xt_align already, it's best for userspace to do
the same.
But that doesn't work for older kernels. Please don't dismiss
compatibility issues that easily. Sometimes things unfortunately
do slip through, but I expect people to do their best to fix the
problem properly when this happens.
I compiled myself an ARM crosscompiler, just to see what's going on. Not
that I could run the binaries, but I could at least look at the objdump
output. The first impression was: "the state before the supposed
regression was introduced could not have worked on ARM in the first
place had I run this".
It turns out that ebtables is completely unusable on at least three
arches with given ABI configurations even if things were still
calculated against ebt_replace instead of _xt_align. One case has been
verified by me since it's consumer hardware, and it surprises me
the Debian project has not found this earlier, because they actually
produced one affected binary distribution in the past (x86 with
k64_u32).
Affected arches are all with k64_u32. (Perhaps almost all — I did not
recall seeing it on sparc64, and, as I am just checking up on ebtables's
Makefile, it has a hack for sparc.) The other configuration I see
problems in is a (rather normal) k32_u32 ARM setup with a kernel
compiled with CONFIG_EABI=no.
The userspace patch proposed by Sachin Nasap is, IMHO, one to fix the
alignment problems (both old and recent) in one clap.
Thanks, I'll have a look at it this weekend.
cheers,
Bart
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