Edit report at https://bugs.php.net/bug.php?id=64187&edit=1
ID: 64187
User updated by: nachms+php at gmail dot com
Reported by: nachms+php at gmail dot com
Summary: CGI/FastCGI truncates input to modulo 4GB
Status: Open
Type: Bug
Package: Streams related
Operating System: Linux
PHP Version: 5.4.11
Block user comment: N
Private report: N
New Comment:
payden, thanks for the info. It's nice to know that the fix works properly with FPM builds as
well, and even on 32-bit!
I wouldn't mind testing that out myself. Can you post your C FCGI client? Thanks.
Allowing others to easily test and report if they can reproduce the problem or not in other cases
may help the PHP developers too (or not, no idea how important the votes and statistics are).
Previous Comments:
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[2013-02-19 05:20:31] payden at paydensutherland dot com
Hey,
I did a little testing and have some findings to share. I believe your fix
works perfectly fine with php-fpm and it does not in fact need to be bounded for
fcgi_read to work correctly. I wanted to duplicate your initial test over fpm
and see what happened. With the the bounding in place, I got some weird results
with fpm. The PHP script stopped reading and finished executing at exactly
2147483647 bytes. (signed 32-bit int max) When I commented the MIN() out and
rebuilt, the script read the entirety of the 4296015872 bytes I sent it and
reported reading that amount. I used the same PHP code you used for the test
and a hacked together C FCGI client. I am using a 32-bit build of PHP. I don't
know if any of this information is useful for you, but I was bored and would
kind of like to start watching bugs and getting involved a little bit. Let me
know if I'm going about it the wrong way!
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[2013-02-19 04:32:33] nachms+php at gmail dot com
Problems in PHP are also a bit larger than I described here, although perhaps should be filed as a
separate bug.
32-bit OSs generally have "large file support", and can support handling data at much
larger than 4GB. On most UNIXs, getconf can indicate appropriate flags to enable such support. On
Windows, large file support is always available.
Ideally PHP should ensure such support is available and properly used. For starters, Content-Length
header is stored within a long. It should be stored in a type guaranteed to be 64 bits, and not
depend if the system itself is 32 or 64 bit.
It is okay to limit the amount of data that can be read at once is limited to 32-bit, even on a
64-bit platform. But the overall size on files or input streams from pipes and sockets should not
be.
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[2013-02-19 02:31:22] payden at paydensutherland dot com
Oh, I'm sorry. I must have misread it before. I see you're not ignoring
count_bytes. You're just taking out the MIN() on count_bytes, and remaining data
to be read. Let me keep my mouth shut until I come up with something intelligent
to say. :)
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[2013-02-19 02:27:04] payden at paydensutherland dot com
I may be way off here, but from what I can see in SAPI.c (for 5.4.11, line 266 is
where the callback is invoked), count_bytes is the number of bytes that the
sapi_module_struct->read_post callback can safely stuff in the buffer without
overflowing its bounds. I think ignoring count_bytes in the callback is probably
a bad idea. Just my two cents. I'll be looking more into it and I'll post here
if I come up with a solution.
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[2013-02-11 19:27:39] nachms+php at gmail dot com
Due to lack of comments as mentioned above, I'm unsure what the problematic loop is needed for.
However thinking more about it, perhaps it's needed for pipelining or multiplexing?
In which case, changing read_post_bytes in SAPI.h from int to long, and removing the uint cast from
SG(request_info).content_length may be the correct solution.
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