Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.12 33/43] s390/mm: fix BUG_ON in crst_table_upgrade | Date | Fri, 8 Sep 2017 15:19:21 +0200 |
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4.12-stable review patch. If anyone has any objections, please let me know.
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From: Martin Schwidefsky <schwidefsky@de.ibm.com>
commit 8ab867cb0806a8e195de161fd8883a0578d1d050 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: 9b11c7912d00 ("s390/mm: simplify arch_get_unmapped_area[_topdown]") Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- arch/s390/mm/mmap.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/arch/s390/mm/mmap.c +++ b/arch/s390/mm/mmap.c @@ -119,7 +119,8 @@ arch_get_unmapped_area(struct file *filp return addr; 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); if (rc) return (unsigned long) rc; @@ -183,7 +184,8 @@ arch_get_unmapped_area_topdown(struct fi } 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); if (rc) return (unsigned long) rc;
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