5b3efa4f14
pfn_valid can be wrong when parsing a invalid pfn whose phys address exceeds BITS_PER_LONG as the MSB will be trimed when shifted. The issue originally arise from bellowing call stack, which corresponding to an access of the /proc/kpageflags from userspace with a invalid pfn parameter and leads to kernel panic. [46886.723249] c7 [<c031ff98>] (stable_page_flags) from [<c03203f8>] [46886.723264] c7 [<c0320368>] (kpageflags_read) from [<c0312030>] [46886.723280] c7 [<c0311fb0>] (proc_reg_read) from [<c02a6e6c>] [46886.723290] c7 [<c02a6e24>] (__vfs_read) from [<c02a7018>] [46886.723301] c7 [<c02a6f74>] (vfs_read) from [<c02a778c>] [46886.723315] c7 [<c02a770c>] (SyS_pread64) from [<c0108620>] (ret_fast_syscall+0x0/0x28) Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
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.