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6bf8ab7774
During wacom_parse_and_register() the code calls wacom_devm_kfifo_alloc
to allocate a fifo. During this operation it passes kfifo_alloc a
fifo_size of 0. Kfifo attempts to round the size passed to it to the
next power of 2 via roundup_pow_of_two (queue-type data structures
do this to maintain efficiency of operations).
However during this phase a problem arises when the roundup_pow_of_two()
function utilises a shift exponent of fls_long(n-1), where n is the
fifo_size. Since n is 0 in this case and n is also an unsigned long,
doing n-1 causes unsigned integer wrap-around to occur making the
fifo_size 4294967295. So the code effectively does fls_long(4294967295)
which results in 64. Returning back to roundup_pow_of_two(), the code
utilises a shift exponent of 64. When a shift exponent of 64 is used
on a 64-bit type such as 1UL it results in a shift-out-of-bounds.
The root cause of the issue seems to stem from insufficient validation
of wacom_compute_pktlen(), since in this case the fifo_size comes
from wacom_wac->features.pktlen. During wacom_parse_and_register()
the wacom_compute_pktlen() function sets the pktlen as 0.
To fix this, we should handle cases where wacom_compute_pktlen()
results in 0.
Reported-by: syzbot <syzbot+d5204cbbdd921f1f7cad@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=d5204cbbdd921f1f7cad
Fixes:
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|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| 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 reStructuredText 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.