From 1e1fc133483ef3b56c20bf3cd9241146c41042f8 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Tue, 30 May 2017 00:29:38 -0400 Subject: [PATCH] compat_{get,put}_bitmap(): use unsafe_{get,put}_user() unroll the inner loops, while we are at it Signed-off-by: Al Viro --- include/linux/compat.h | 3 +- kernel/compat.c | 81 +++++++++++++++--------------------------- 2 files changed, 29 insertions(+), 55 deletions(-) diff --git a/include/linux/compat.h b/include/linux/compat.h index 1c5f3152cbb5..94ceb0348a25 100644 --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -388,8 +388,7 @@ asmlinkage long compat_sys_wait4(compat_pid_t pid, #define BITS_PER_COMPAT_LONG (8*sizeof(compat_long_t)) -#define BITS_TO_COMPAT_LONGS(bits) \ - (((bits)+BITS_PER_COMPAT_LONG-1)/BITS_PER_COMPAT_LONG) +#define BITS_TO_COMPAT_LONGS(bits) DIV_ROUND_UP(bits, BITS_PER_COMPAT_LONG) long compat_get_bitmap(unsigned long *mask, const compat_ulong_t __user *umask, unsigned long bitmap_size); diff --git a/kernel/compat.c b/kernel/compat.c index 860f674fa556..9c2a8f3788d5 100644 --- a/kernel/compat.c +++ b/kernel/compat.c @@ -871,84 +871,59 @@ int get_compat_sigevent(struct sigevent *event, long compat_get_bitmap(unsigned long *mask, const compat_ulong_t __user *umask, unsigned long bitmap_size) { - int i, j; - unsigned long m; - compat_ulong_t um; unsigned long nr_compat_longs; /* align bitmap up to nearest compat_long_t boundary */ bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG); + nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size); if (!access_ok(VERIFY_READ, umask, bitmap_size / 8)) return -EFAULT; - nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size); - - for (i = 0; i < BITS_TO_LONGS(bitmap_size); i++) { - m = 0; - - for (j = 0; j < sizeof(m)/sizeof(um); j++) { - /* - * We dont want to read past the end of the userspace - * bitmap. We must however ensure the end of the - * kernel bitmap is zeroed. - */ - if (nr_compat_longs) { - nr_compat_longs--; - if (__get_user(um, umask)) - return -EFAULT; - } else { - um = 0; - } - - umask++; - m |= (long)um << (j * BITS_PER_COMPAT_LONG); - } - *mask++ = m; + user_access_begin(); + while (nr_compat_longs > 1) { + compat_ulong_t l1, l2; + unsafe_get_user(l1, umask++, Efault); + unsafe_get_user(l2, umask++, Efault); + *mask++ = ((unsigned long)l2 << BITS_PER_COMPAT_LONG) | l1; + nr_compat_longs -= 2; } - + if (nr_compat_longs) + unsafe_get_user(*mask, umask++, Efault); + user_access_end(); return 0; + +Efault: + user_access_end(); + return -EFAULT; } long compat_put_bitmap(compat_ulong_t __user *umask, unsigned long *mask, unsigned long bitmap_size) { - int i, j; - unsigned long m; - compat_ulong_t um; unsigned long nr_compat_longs; /* align bitmap up to nearest compat_long_t boundary */ bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG); + nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size); if (!access_ok(VERIFY_WRITE, umask, bitmap_size / 8)) return -EFAULT; - nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size); - - for (i = 0; i < BITS_TO_LONGS(bitmap_size); i++) { - m = *mask++; - - for (j = 0; j < sizeof(m)/sizeof(um); j++) { - um = m; - - /* - * We dont want to write past the end of the userspace - * bitmap. - */ - if (nr_compat_longs) { - nr_compat_longs--; - if (__put_user(um, umask)) - return -EFAULT; - } - - umask++; - m >>= 4*sizeof(um); - m >>= 4*sizeof(um); - } + user_access_begin(); + while (nr_compat_longs > 1) { + unsigned long m = *mask++; + unsafe_put_user((compat_ulong_t)m, umask++, Efault); + unsafe_put_user(m >> BITS_PER_COMPAT_LONG, umask++, Efault); + nr_compat_longs -= 2; } - + if (nr_compat_longs) + unsafe_put_user((compat_ulong_t)*mask, umask++, Efault); + user_access_end(); return 0; +Efault: + user_access_end(); + return -EFAULT; } void -- 2.39.5