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This code will likely crash if we try to do a zero byte write. The code
looks like this:
/* strip trailing whitespace */
for (i = count - 1; i > 0; i--)
if (isspace(buf[i]))
...
We're writing zero bytes so count = 0. You would think that "count - 1"
would be negative one, but because "i" is unsigned it is a large
positive numer instead. The "i > 0" condition is true and the "buf[i]"
access will be out of bounds.
The fix is to make "i" signed and now everything works as expected. The
upper bound of "count" is capped in __kernel_write() at MAX_RW_COUNT so
we don't have to worry about it being higher than INT_MAX.
Fixes:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.