Messages in this thread | | | Date | Sat, 25 Feb 2006 18:05:21 +0000 | From | Russell King <> | Subject | Re: [PATCH 3/7] inflate pt1: clean up input logic |
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On Sat, Feb 25, 2006 at 08:54:12AM -0600, Matt Mackall wrote: > On Sat, Feb 25, 2006 at 08:49:55AM +0000, Russell King wrote: > > On Sat, Feb 25, 2006 at 12:51:36AM -0600, Matt Mackall wrote: > > > On Fri, Feb 24, 2006 at 10:19:09PM +0000, Russell King wrote: > > > > How does this change handle the case where we run out of input data? > > > > This condition needs to be handled explicitly because the inflate > > > > functions can infinitely loop. > > > > > > And if you look at the current users, you'll see that only two of 15 > > > actually use it. > > > > Sorry, I don't understand the relevance of your comment. > > The other 13 did the right thing, namely halt in get_byte. Without > adding a magic goto inside of a macro. > > > Please do not back out this fix. > > The backing out is only temporary, as I stated in my message. That > said, it should have never gone in.
Nevertheless, it's a wilful re-introduction of a real bug.
> > > > Relying on a bit pattern returned by get_byte() is how this code > > > > pre-fix used to work, and it caused several confused bug reports. > > > > > > Just about everywhere, get_byte prints an error message and halts. > > > > And the cases where it doesn't halt is the important case. > > Again, current state of things. Did you read the rest of my message?
And you're failing to see the problem.
> The end result is that it will halt in all cases. This code _will_not_ > infinitely loop. Instead, it will dereference null or print a > diagnostic. I can add another patch to make sure it prints a nice > diagnostic in all cases if you care, but I don't think it's terribly > important.
Not acceptable.
We DO NOT want to halt in ALL cases. There is ONE case where we definitely do want to GRACEFULLY fail and _NOT_ halt the kernel.
It seems that you're missing this case - the case where lib/inflate.c is used elsewhere in the kernel apart from the boot time decompressors. The behaviour you describe is perfectly reasonable for the boot time decompressors, but _NOT_ once the kernel has been decompressed.
Sorry, I'm disgusted that it's come to this to get my point across. Do I really have to use capital letters in an attempt to convey the point?
-- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 Serial core - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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