lkml.org 
[lkml]   [2021]   [Nov]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] powerpc/code-patching: Relax verification of patchability
Date
Commit 8b8a8f0ab3f5 ("powerpc/code-patching: Improve verification of
patchability") introduced a stricter verification of the patched
area by checking it is proper kernel text.

But as least two usages of patch_instruction() fall outside:
- Code patching selftests, which use stack and vmalloc space.
- Ftrace

So for the time being, partially revert commit 8b8a8f0ab3f5 and add
a onetime warning:

Running code patching self-tests ...
patch_instruction() called on invalid text address 0xe1011e58 from test_code_patching+0x34/0xd6c

Reported-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Fixes: 8b8a8f0ab3f5 ("powerpc/code-patching: Improve verification of patchability")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
arch/powerpc/lib/code-patching.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
index 1dd636a85cc1..c87eea773930 100644
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c
@@ -190,9 +190,13 @@ static int do_patch_instruction(u32 *addr, struct ppc_inst instr)
int patch_instruction(u32 *addr, struct ppc_inst instr)
{
/* Make sure we aren't patching a freed init section */
- if (!kernel_text_address((unsigned long)addr))
+ if (system_state >= SYSTEM_FREEING_INITMEM && init_section_contains(addr, 4))
return 0;

+ if (!kernel_text_address((unsigned long)addr))
+ pr_warn_once("%s() called on invalid text address 0x%p from %pS\n",
+ __func__, addr, __builtin_return_address(0));
+
return do_patch_instruction(addr, instr);
}
NOKPROBE_SYMBOL(patch_instruction);
--
2.33.1
\
 
 \ /
  Last update: 2021-11-26 08:43    [W:0.056 / U:0.412 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site