From: Christoph Hellwig <hch@xxxxxx> Subject: syscalls: use uaccess_kernel in addr_limit_user_check Patch series "clean up address limit helpers", v2. In preparation for eventually phasing out direct use of set_fs(), this series removes the segment_eq() arch helper that is only used to implement or duplicate the uaccess_kernel() API, and then adds descriptive helpers to force the kernel address limit. This patch (of 6): Use the uaccess_kernel helper instead of duplicating it. [hch@xxxxxx: arm: don't call addr_limit_user_check for nommu] Link: http://lkml.kernel.org/r/20200721045834.GA9613@xxxxxx Link: http://lkml.kernel.org/r/20200714105505.935079-1-hch@xxxxxx Link: http://lkml.kernel.org/r/20200710135706.537715-1-hch@xxxxxx Link: http://lkml.kernel.org/r/20200710135706.537715-2-hch@xxxxxx Signed-off-by: Christoph Hellwig <hch@xxxxxx> Acked-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Tested-by: Guenter Roeck <linux@xxxxxxxxxxxx> Cc: Nick Hu <nickhu@xxxxxxxxxxxxx> Cc: Greentime Hu <green.hu@xxxxxxxxx> Cc: Vincent Chen <deanbo422@xxxxxxxxx> Cc: Paul Walmsley <paul.walmsley@xxxxxxxxxx> Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx> Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/arm/kernel/signal.c | 2 ++ include/linux/syscalls.h | 2 +- 2 files changed, 3 insertions(+), 1 deletion(-) --- a/arch/arm/kernel/signal.c~syscalls-use-uaccess_kernel-in-addr_limit_user_check +++ a/arch/arm/kernel/signal.c @@ -713,7 +713,9 @@ struct page *get_signal_page(void) /* Defer to generic check */ asmlinkage void addr_limit_check_failed(void) { +#ifdef CONFIG_MMU addr_limit_user_check(); +#endif } #ifdef CONFIG_DEBUG_RSEQ --- a/include/linux/syscalls.h~syscalls-use-uaccess_kernel-in-addr_limit_user_check +++ a/include/linux/syscalls.h @@ -263,7 +263,7 @@ static inline void addr_limit_user_check return; #endif - if (CHECK_DATA_CORRUPTION(!segment_eq(get_fs(), USER_DS), + if (CHECK_DATA_CORRUPTION(uaccess_kernel(), "Invalid address limit on user-mode return")) force_sig(SIGKILL); _
