From 52149ba6b0ddf3e9d965257cc0513193650b3ea8 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Thu, 28 Sep 2006 16:56:03 +0200 Subject: [PATCH] [S390] user readable uninitialised kernel memory. A user space program can read uninitialised kernel memory by appending to a file from a bad address and then reading the result back. The cause is the copy_from_user function that does not clear the remaining bytes of the kernel buffer after it got a fault on the user space address. Signed-off-by: Martin Schwidefsky --- arch/s390/lib/uaccess_mvcos.c | 22 +++++++++++++++------ arch/s390/lib/uaccess_std.c | 36 +++++++++++++++++++++++++---------- 2 files changed, 42 insertions(+), 16 deletions(-) diff --git a/arch/s390/lib/uaccess_mvcos.c b/arch/s390/lib/uaccess_mvcos.c index 86c96d6c191a..121b2935a422 100644 --- a/arch/s390/lib/uaccess_mvcos.c +++ b/arch/s390/lib/uaccess_mvcos.c @@ -35,7 +35,7 @@ size_t copy_from_user_mvcos(size_t size, const void __user *ptr, void *x) tmp1 = -4096UL; asm volatile( "0: .insn ss,0xc80000000000,0(%0,%2),0(%1),0\n" - " jz 4f\n" + " jz 7f\n" "1:"ALR" %0,%3\n" " "SLR" %1,%3\n" " "SLR" %2,%3\n" @@ -44,13 +44,23 @@ size_t copy_from_user_mvcos(size_t size, const void __user *ptr, void *x) " nr %4,%3\n" /* %4 = (ptr + 4095) & -4096 */ " "SLR" %4,%1\n" " "CLR" %0,%4\n" /* copy crosses next page boundary? */ - " jnh 5f\n" + " jnh 4f\n" "3: .insn ss,0xc80000000000,0(%4,%2),0(%1),0\n" " "SLR" %0,%4\n" - " j 5f\n" - "4:"SLR" %0,%0\n" - "5: \n" - EX_TABLE(0b,2b) EX_TABLE(3b,5b) + " "ALR" %2,%4\n" + "4:"LHI" %4,-1\n" + " "ALR" %4,%0\n" /* copy remaining size, subtract 1 */ + " bras %3,6f\n" /* memset loop */ + " xc 0(1,%2),0(%2)\n" + "5: xc 0(256,%2),0(%2)\n" + " la %2,256(%2)\n" + "6:"AHI" %4,-256\n" + " jnm 5b\n" + " ex %4,0(%3)\n" + " j 8f\n" + "7:"SLR" %0,%0\n" + "8: \n" + EX_TABLE(0b,2b) EX_TABLE(3b,4b) : "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2) : "d" (reg0) : "cc", "memory"); return size; diff --git a/arch/s390/lib/uaccess_std.c b/arch/s390/lib/uaccess_std.c index 9a4d4a29ea79..f44f0078b354 100644 --- a/arch/s390/lib/uaccess_std.c +++ b/arch/s390/lib/uaccess_std.c @@ -35,25 +35,35 @@ size_t copy_from_user_std(size_t size, const void __user *ptr, void *x) tmp1 = -256UL; asm volatile( "0: mvcp 0(%0,%2),0(%1),%3\n" - " jz 5f\n" + " jz 8f\n" "1:"ALR" %0,%3\n" " la %1,256(%1)\n" " la %2,256(%2)\n" "2: mvcp 0(%0,%2),0(%1),%3\n" " jnz 1b\n" - " j 5f\n" + " j 8f\n" "3: la %4,255(%1)\n" /* %4 = ptr + 255 */ " "LHI" %3,-4096\n" " nr %4,%3\n" /* %4 = (ptr + 255) & -4096 */ " "SLR" %4,%1\n" " "CLR" %0,%4\n" /* copy crosses next page boundary? */ - " jnh 6f\n" + " jnh 5f\n" "4: mvcp 0(%4,%2),0(%1),%3\n" " "SLR" %0,%4\n" - " j 6f\n" - "5:"SLR" %0,%0\n" - "6: \n" - EX_TABLE(0b,3b) EX_TABLE(2b,3b) EX_TABLE(4b,6b) + " "ALR" %2,%4\n" + "5:"LHI" %4,-1\n" + " "ALR" %4,%0\n" /* copy remaining size, subtract 1 */ + " bras %3,7f\n" /* memset loop */ + " xc 0(1,%2),0(%2)\n" + "6: xc 0(256,%2),0(%2)\n" + " la %2,256(%2)\n" + "7:"AHI" %4,-256\n" + " jnm 6b\n" + " ex %4,0(%3)\n" + " j 9f\n" + "8:"SLR" %0,%0\n" + "9: \n" + EX_TABLE(0b,3b) EX_TABLE(2b,3b) EX_TABLE(4b,5b) : "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2) : : "cc", "memory"); return size; @@ -67,16 +77,22 @@ size_t copy_from_user_std_small(size_t size, const void __user *ptr, void *x) asm volatile( "0: mvcp 0(%0,%2),0(%1),%3\n" " "SLR" %0,%0\n" - " j 3f\n" + " j 5f\n" "1: la %4,255(%1)\n" /* %4 = ptr + 255 */ " "LHI" %3,-4096\n" " nr %4,%3\n" /* %4 = (ptr + 255) & -4096 */ " "SLR" %4,%1\n" " "CLR" %0,%4\n" /* copy crosses next page boundary? */ - " jnh 3f\n" + " jnh 5f\n" "2: mvcp 0(%4,%2),0(%1),%3\n" " "SLR" %0,%4\n" - "3:\n" + " "ALR" %2,%4\n" + "3:"LHI" %4,-1\n" + " "ALR" %4,%0\n" /* copy remaining size, subtract 1 */ + " bras %3,4f\n" + " xc 0(1,%2),0(%2)\n" + "4: ex %4,0(%3)\n" + "5:\n" EX_TABLE(0b,1b) EX_TABLE(2b,3b) : "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2) : : "cc", "memory"); -- 2.30.2