From b69fb7699c92f85991672fc144b0adb7c717fbc8 Mon Sep 17 00:00:00 2001 From: David Ahern Date: Mon, 15 Jun 2015 16:15:45 -0400 Subject: [PATCH] sparc64: perf: Add sanity checking on addresses in user stack Processes are getting killed (sigbus or segv) while walking userspace callchains when using perf. In some instances I have seen ufp = 0x7ff which does not seem like a proper stack address. This patch adds a function to run validity checks against the address before attempting the copy_from_user. The checks are copied from the x86 version as a start point with the addition of a 4-byte alignment check. Signed-off-by: David Ahern Signed-off-by: David S. Miller --- arch/sparc/include/asm/uaccess_64.h | 22 ++++++++++++++++++++++ arch/sparc/kernel/perf_event.c | 13 +++++++++++++ 2 files changed, 35 insertions(+) diff --git a/arch/sparc/include/asm/uaccess_64.h b/arch/sparc/include/asm/uaccess_64.h index a35194b7dba0..ea6e9a20f3ff 100644 --- a/arch/sparc/include/asm/uaccess_64.h +++ b/arch/sparc/include/asm/uaccess_64.h @@ -49,6 +49,28 @@ do { \ __asm__ __volatile__ ("wr %%g0, %0, %%asi" : : "r" ((val).seg)); \ } while(0) +/* + * Test whether a block of memory is a valid user space address. + * Returns 0 if the range is valid, nonzero otherwise. + */ +static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit) +{ + if (__builtin_constant_p(size)) + return addr > limit - size; + + addr += size; + if (addr < size) + return true; + + return addr > limit; +} + +#define __range_not_ok(addr, size, limit) \ +({ \ + __chk_user_ptr(addr); \ + __chk_range_not_ok((unsigned long __force)(addr), size, limit); \ +}) + static inline int __access_ok(const void __user * addr, unsigned long size) { return 1; diff --git a/arch/sparc/kernel/perf_event.c b/arch/sparc/kernel/perf_event.c index 48387be665e9..a665e3f8c6c6 100644 --- a/arch/sparc/kernel/perf_event.c +++ b/arch/sparc/kernel/perf_event.c @@ -1741,6 +1741,16 @@ void perf_callchain_kernel(struct perf_callchain_entry *entry, } while (entry->nr < PERF_MAX_STACK_DEPTH); } +static inline int +valid_user_frame(const void __user *fp, unsigned long size) +{ + /* addresses should be at least 4-byte aligned */ + if (((unsigned long) fp) & 3) + return 0; + + return (__range_not_ok(fp, size, TASK_SIZE) == 0); +} + static void perf_callchain_user_64(struct perf_callchain_entry *entry, struct pt_regs *regs) { @@ -1753,6 +1763,9 @@ static void perf_callchain_user_64(struct perf_callchain_entry *entry, unsigned long pc; usf = (struct sparc_stackf __user *)ufp; + if (!valid_user_frame(usf, sizeof(sf))) + break; + if (__copy_from_user_inatomic(&sf, usf, sizeof(sf))) break; -- 2.11.0