commit: 6f3946b421395ff853bc0bcdab9c26b50ebbba8f From: Steven J. Magnani <[email protected]> Date: Thu, 10 Feb 2011 12:12:13 -0600 Subject: [PATCH] microblaze: Fix /dev/zero corruption from __clear_user()
A userland read of more than PAGE_SIZE bytes from /dev/zero results in (a) not all of the bytes returned being zero, and (b) memory corruption due to zeroing of bytes beyond the user buffer. This is caused by improper constraints on the assembly __clear_user function. The constrints don't indicate to the compiler that the pointer argument is modified. Since the function is inline, this results in double-incrementing of the pointer when __clear_user() is invoked through a multi-page read() of /dev/zero. Signed-off-by: Steven J. Magnani <[email protected]> Acked-by: Michal Simek <[email protected]> CC: [email protected] --- arch/microblaze/include/asm/uaccess.h | 8 ++++---- 1 files changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/microblaze/include/asm/uaccess.h b/arch/microblaze/include/asm/uaccess.h index d840f4a..5bb95a1 100644 --- a/arch/microblaze/include/asm/uaccess.h +++ b/arch/microblaze/include/asm/uaccess.h @@ -120,16 +120,16 @@ static inline unsigned long __must_check __clear_user(void __user *to, { /* normal memset with two words to __ex_table */ __asm__ __volatile__ ( \ - "1: sb r0, %2, r0;" \ + "1: sb r0, %1, r0;" \ " addik %0, %0, -1;" \ " bneid %0, 1b;" \ - " addik %2, %2, 1;" \ + " addik %1, %1, 1;" \ "2: " \ __EX_TABLE_SECTION \ ".word 1b,2b;" \ ".previous;" \ - : "=r"(n) \ - : "0"(n), "r"(to) + : "=r"(n), "=r"(to) \ + : "0"(n), "1"(to) ); return n; } _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
