Commit e3b9fb20 authored by Martin Schwidefsky's avatar Martin Schwidefsky Committed by Greg Kroah-Hartman

s390/mm: fix BUG_ON in crst_table_upgrade

commit 8ab867cb upstream.

A 31-bit compat process can force a BUG_ON in crst_table_upgrade
with specific, invalid mmap calls, e.g.

   mmap((void*) 0x7fff8000, 0x10000, 3, 32, -1, 0)

The arch_get_unmapped_area[_topdown] functions miss an if condition
in the decision to do a page table upgrade.

[ms: Backport to 4.12, minor context change]

Fixes: 9b11c791 ("s390/mm: simplify arch_get_unmapped_area[_topdown]")
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 2ce0e049
...@@ -119,7 +119,8 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr, ...@@ -119,7 +119,8 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
return addr; return addr;
check_asce_limit: check_asce_limit:
if (addr + len > current->mm->context.asce_limit) { if (addr + len > current->mm->context.asce_limit &&
addr + len <= TASK_SIZE) {
rc = crst_table_upgrade(mm); rc = crst_table_upgrade(mm);
if (rc) if (rc)
return (unsigned long) rc; return (unsigned long) rc;
...@@ -183,7 +184,8 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, ...@@ -183,7 +184,8 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
} }
check_asce_limit: check_asce_limit:
if (addr + len > current->mm->context.asce_limit) { if (addr + len > current->mm->context.asce_limit &&
addr + len <= TASK_SIZE) {
rc = crst_table_upgrade(mm); rc = crst_table_upgrade(mm);
if (rc) if (rc)
return (unsigned long) rc; return (unsigned long) rc;
......
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