c5c07c5958
This is another instance of incorrect use of list iterator and
checking it for NULL.
The list iterator value 'map' will *always* be set and non-NULL
by list_for_each_entry(), so it is incorrect to assume that the
iterator value will be NULL if the list is empty (in this case, the
check 'if (!map) {' will always be false and never exit as expected).
To fix the bug, use a new variable 'iter' as the list iterator,
while use the original variable 'map' as a dedicated pointer to
point to the found element.
Without this patch, Kernel crashes with below trace:
Unable to handle kernel access to user memory outside uaccess routines
at virtual address 0000ffff7fb03750
...
Call trace:
fastrpc_map_create+0x70/0x290 [fastrpc]
fastrpc_req_mem_map+0xf0/0x2dc [fastrpc]
fastrpc_device_ioctl+0x138/0xc60 [fastrpc]
__arm64_sys_ioctl+0xa8/0xec
invoke_syscall+0x48/0x114
el0_svc_common.constprop.0+0xd4/0xfc
do_el0_svc+0x28/0x90
el0_svc+0x3c/0x130
el0t_64_sync_handler+0xa4/0x130
el0t_64_sync+0x18c/0x190
Code: 14000016 f94000a5 eb05029f 54000260 (b94018a6)
---[ end trace 0000000000000000 ]---
Fixes: 5c1b97c7d7b7 ("misc: fastrpc: add support for FASTRPC_IOCTL_MEM_MAP/UNMAP")
Cc: stable@vger.kernel.org
Reported-by: Jan Jablonsky <jjablonsky@snapchat.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220518152353.13058-1-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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.