| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.4 172/177] powerpc: Define arch_is_kernel_initmem_freed() for lockdep | Date | Mon, 16 Dec 2019 18:50:28 +0100 |
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From: Michael Ellerman <mpe@ellerman.id.au>
commit 6f07048c00fd100ed8cab66c225c157e0b6c0a50 upstream.
Under certain circumstances, we hit a warning in lockdep_register_key:
if (WARN_ON_ONCE(static_obj(key))) return;
This occurs when the key falls into initmem that has since been freed and can now be reused. This has been observed on boot, and under memory pressure.
Define arch_is_kernel_initmem_freed(), which allows lockdep to correctly identify this memory as dynamic.
This fixes a bug picked up by the powerpc64 syzkaller instance where we hit the WARN via alloc_netdev_mqs.
Reported-by: Qian Cai <cai@lca.pw> Reported-by: ppc syzbot c/o Andrew Donnellan <ajd@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Daniel Axtens <dja@axtens.net> Link: https://lore.kernel.org/r/87lfs4f7d6.fsf@dja-thinkpad.axtens.net Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- arch/powerpc/include/asm/sections.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
--- a/arch/powerpc/include/asm/sections.h +++ b/arch/powerpc/include/asm/sections.h @@ -5,8 +5,22 @@ #include <linux/elf.h> #include <linux/uaccess.h> + +#define arch_is_kernel_initmem_freed arch_is_kernel_initmem_freed + #include <asm-generic/sections.h> +extern bool init_mem_is_free; + +static inline int arch_is_kernel_initmem_freed(unsigned long addr) +{ + if (!init_mem_is_free) + return 0; + + return addr >= (unsigned long)__init_begin && + addr < (unsigned long)__init_end; +} + extern char __head_end[]; #ifdef __powerpc64__
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