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| author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2006-09-28 16:56:03 +0200 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2006-09-28 16:56:03 +0200 |
| commit | 52149ba6b0ddf3e9d965257cc0513193650b3ea8 (patch) | |
| tree | af8097516b3cd9d9f2397080e4cf81414fd4172a /arch/s390/lib/uaccess_mvcos.c | |
| parent | 51dced544e3964b684afc99282ceceaa384b16a8 (diff) | |
| download | linux-3.10-52149ba6b0ddf3e9d965257cc0513193650b3ea8.tar.gz linux-3.10-52149ba6b0ddf3e9d965257cc0513193650b3ea8.tar.bz2 linux-3.10-52149ba6b0ddf3e9d965257cc0513193650b3ea8.zip | |
[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 <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/lib/uaccess_mvcos.c')
| -rw-r--r-- | arch/s390/lib/uaccess_mvcos.c | 22 |
1 files changed, 16 insertions, 6 deletions
diff --git a/arch/s390/lib/uaccess_mvcos.c b/arch/s390/lib/uaccess_mvcos.c index 86c96d6c191..121b2935a42 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; |