Messages in this thread | | | Date | Fri, 26 Nov 2021 09:49:00 +0100 | Subject | Re: [PATCH] powerpc/code-patching: Relax verification of patchability | From | Christophe Leroy <> |
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Le 26/11/2021 à 08:39, Christophe Leroy a écrit : > 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)); > +
May it be better to use pr_warn_ratelimited() instead in order to catch more than the first occurence ?
> return do_patch_instruction(addr, instr); > } > NOKPROBE_SYMBOL(patch_instruction); >
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