Messages in this thread | | | From | Linus Torvalds <> | Date | Fri, 18 May 2018 20:33:37 -0700 | Subject | Re: [PATCH] procfs: fix mmap() for /proc/vmcore |
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On Fri, May 18, 2018 at 8:20 PM Linus Torvalds < torvalds@linux-foundation.org> wrote:
> I'd *much* rather just set FMODE_UNSIGNED_OFFSET for /proc/vmcore _only_, > rather than open up all proc files to issues with 4G+ offsets.
Hmm. I was going to point to the s_maxbytes check in rw_verify_area() and ask you how that ever worked for that file, but it's not there, the s_maxbyte checks are only in lseek and in do_splice().
So apparently we protect against llseek + read/write, but we don't protect against pread64/pwrite64 having offset overflows..
That's crazy. That makes all the s_maxbytes protection much less effective than it should be. Filesystems that don't get the 64-bit case right will screw up pread64 and friends.
Al, I'm missing something. Did we always have this gaping hole where we didn't actually check s_maxbytes against read/write, only generic_file_llseek? Apparently.
Linus
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