Messages in this thread | | | Date | Tue, 12 Mar 2019 10:37:54 +0100 | From | Pavel Machek <> | Subject | Re: [PATCH 1/4] elf: don't be afraid of overflow |
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On Mon 2019-03-11 20:10:06, Alexey Dobriyan wrote: > On Mon, Mar 11, 2019 at 12:04:23PM +0100, Pavel Machek wrote: > > On Mon 2019-02-04 23:27:15, Alexey Dobriyan wrote: > > > Number of ELF program headers is 16-bit by spec, so total size > > > comfortably fits into "unsigned int". > > > > If it can't overflow, gcc should know too, and optimize checks > > out... right? > > Turns out it doesn't.
Tells me you are doing something wrong.
> > > @@ -429,13 +430,9 @@ static struct elf_phdr *load_elf_phdrs(struct elfhdr *elf_ex, > > > goto out; > > > > > > /* Sanity check the number of program headers... */ > > > - if (elf_ex->e_phnum < 1 || > > > - elf_ex->e_phnum > 65536U / sizeof(struct elf_phdr)) > > > - goto out; > > > - > > > /* ...and their total size. */ > > > > This is just wrong. You removed check for zero, and I'm pretty sure > > sizeof() is not 1, so this one can trigger, too. > > No. ->e_phnum is 65535 max.
That does not invalidate my argument.
Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html [unhandled content-type:application/pgp-signature] | |