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2fc1c63d27
In addition to checking whether a page is reserved before allocating
it to highmem, verify that it is valid memory.
Otherwise the kernel Oopses as below:
mem auto-init: stack:off, heap alloc:off, heap free:off
Kernel attempted to read user page (7df58) - exploit attempt? (uid: 0)
BUG: Unable to handle kernel data access on read at 0x0007df58
Faulting instruction address: 0xc01c8348
Oops: Kernel access of bad area, sig: 11 [#1]
BE PAGE_SIZE=4K SMP NR_CPUS=2 P2020RDB-PC
Modules linked in:
CPU: 0 PID: 0 Comm: swapper Not tainted 6.0.0-rc2-0caacb197b677410bdac81bc34f05235+ #121
NIP: c01c8348 LR: c01cb2bc CTR: 0000000a
REGS: c10d7e20 TRAP: 0300 Not tainted (6.0.0-rc2-0caacb197b677410bdac81bc34f05235+)
MSR: 00021000 <CE,ME> CR: 48044224 XER: 00000000
DEAR: 0007df58 ESR: 00000000
GPR00: c01cb294 c10d7f10 c1045340 00000001 00000004 c112bcc0 00000015 eedf1000
GPR08: 00000003 0007df58 00000000 f0000000 28044228 00000200 00000000 00000000
GPR16: 00000000 00000000 00000000 0275cb7a c0000000 00000001 0000075f 00000000
GPR24: c1031004 00000000 00000000 00000001 c10f0000 eedf1000 00080000 00080000
NIP free_unref_page_prepare.part.93+0x48/0x60
LR free_unref_page+0x84/0x4b8
Call Trace:
0xeedf1000 (unreliable)
free_unref_page+0x5c/0x4b8
mem_init+0xd0/0x194
start_kernel+0x4c0/0x6d0
set_ivor+0x13c/0x178
Reported-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Fixes: b0e0d68b1c ("powerpc/32: Allow fragmented physical memory")
Tested-by: Pali Rohár <pali@kernel.org>
[mpe: Trim oops]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/f08cca5c46d67399c53262eca48e015dcf1841f9.1663695394.git.christophe.leroy@csgroup.eu
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.