The patch titled Subject: mm/mmap.c: fix arithmetic overflow in __vm_enough_memory() has been removed from the -mm tree. Its filename was mm-fix-arithmetic-overflow-in-__vm_enough_memory.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Roman Gushchin <klamm@xxxxxxxxxxxxxx> Subject: mm/mmap.c: fix arithmetic overflow in __vm_enough_memory() I noticed, that "allowed" can easily overflow by falling below 0, because (total_vm / 32) can be larger than "allowed". The problem occurs in OVERCOMMIT_NONE mode. In this case, a huge allocation can success and overcommit the system (despite OVERCOMMIT_NONE mode). All subsequent allocations will fall (system-wide), so system become unusable. The problem was masked out by commit c9b1d0981fcc ("mm: limit growth of 3% hardcoded other user reserve"), but it's easy to reproduce it on older kernels: 1) set overcommit_memory sysctl to 2 2) mmap() large file multiple times (with VM_SHARED flag) 3) try to malloc() large amount of memory It also can be reproduced on newer kernels, but miss-configured sysctl_user_reserve_kbytes is required. Fix this issue by switching to signed arithmetic here. [akpm@xxxxxxxxxxxxxxxxxxxx: use min_t] Signed-off-by: Roman Gushchin <klamm@xxxxxxxxxxxxxx> Cc: Andrew Shewmaker <agshew@xxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Cc: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx> Reviewed-by: Michal Hocko <mhocko@xxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/mmap.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff -puN mm/mmap.c~mm-fix-arithmetic-overflow-in-__vm_enough_memory mm/mmap.c --- a/mm/mmap.c~mm-fix-arithmetic-overflow-in-__vm_enough_memory +++ a/mm/mmap.c @@ -152,7 +152,7 @@ EXPORT_SYMBOL_GPL(vm_memory_committed); */ int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) { - unsigned long free, allowed, reserve; + long free, allowed, reserve; VM_WARN_ONCE(percpu_counter_read(&vm_committed_as) < -(s64)vm_committed_as_batch * num_online_cpus(), @@ -220,7 +220,7 @@ int __vm_enough_memory(struct mm_struct */ if (mm) { reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10); - allowed -= min(mm->total_vm / 32, reserve); + allowed -= min_t(long, mm->total_vm / 32, reserve); } if (percpu_counter_read_positive(&vm_committed_as) < allowed) _ Patches currently in -mm which might be from klamm@xxxxxxxxxxxxxx are origin.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html