This is a note to let you know that I've just added the patch titled
powerpc/8xx: Fix kernel vs user address comparison
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
powerpc-8xx-fix-kernel-vs-user-address-comparison.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 81ecf86784870a012c628df7e88824618230e628
Author: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Date: Tue Aug 20 19:23:46 2024 +0200
powerpc/8xx: Fix kernel vs user address comparison
[ Upstream commit 65a82e117ffeeab0baf6f871a1cab11a28ace183 ]
Since commit 9132a2e82adc ("powerpc/8xx: Define a MODULE area below
kernel text"), module exec space is below PAGE_OFFSET so not only
space above PAGE_OFFSET, but space above TASK_SIZE need to be seen
as kernel space.
Until now the problem went undetected because by default TASK_SIZE
is 0x8000000 which means address space is determined by just
checking upper address bit. But when TASK_SIZE is over 0x80000000,
PAGE_OFFSET is used for comparison, leading to thinking module
addresses are part of user space.
Fix it by using TASK_SIZE instead of PAGE_OFFSET for address
comparison.
Fixes: 9132a2e82adc ("powerpc/8xx: Define a MODULE area below kernel text")
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://msgid.link/3f574c9845ff0a023b46cb4f38d2c45aecd769bd.1724173828.git.christophe.leroy@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 0d073b9fd52c5..4e409eee42b10 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -40,12 +40,12 @@
#include "head_32.h"
.macro compare_to_kernel_boundary scratch, addr
-#if CONFIG_TASK_SIZE <= 0x80000000 && CONFIG_PAGE_OFFSET >= 0x80000000
+#if CONFIG_TASK_SIZE <= 0x80000000 && MODULES_VADDR >= 0x80000000
/* By simply checking Address >= 0x80000000, we know if its a kernel address */
not. \scratch, \addr
#else
rlwinm \scratch, \addr, 16, 0xfff8
- cmpli cr0, \scratch, PAGE_OFFSET@h
+ cmpli cr0, \scratch, TASK_SIZE@h
#endif
.endm
@@ -403,7 +403,7 @@ FixupDAR:/* Entry point for dcbx workaround. */
mfspr r10, SPRN_SRR0
mtspr SPRN_MD_EPN, r10
rlwinm r11, r10, 16, 0xfff8
- cmpli cr1, r11, PAGE_OFFSET@h
+ cmpli cr1, r11, TASK_SIZE@h
mfspr r11, SPRN_M_TWB /* Get level 1 table */
blt+ cr1, 3f
