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authorJack Morgenstein <jackm@dev.mellanox.co.il>2018-05-02 13:04:25 +0300
committerDoug Ledford <dledford@redhat.com>2018-05-03 15:31:43 -0400
commitb03bcde962606d2ee59a4e9dd470db9ad53c5418 (patch)
tree38e6e9ed39cebf666f2595b3afb5a1669e0ce87b
parent59482a14918b282ca2a98f38c69da5ebeb1107d2 (diff)
downloadlinux-stericsson-b03bcde962606d2ee59a4e9dd470db9ad53c5418.tar.gz
IB/mlx4: Fix integer overflow when calculating optimal MTT size
When the kernel was compiled using the UBSAN option, we saw the following stack trace: [ 1184.827917] UBSAN: Undefined behaviour in drivers/infiniband/hw/mlx4/mr.c:349:27 [ 1184.828114] signed integer overflow: [ 1184.828247] -2147483648 - 1 cannot be represented in type 'int' The problem was caused by calling round_up in procedure mlx4_ib_umem_calc_optimal_mtt_size (on line 349, as noted in the stack trace) with the second parameter (1 << block_shift) (which is an int). The second parameter should have been (1ULL << block_shift) (which is an unsigned long long). (1 << block_shift) is treated by the compiler as an int (because 1 is an integer). Now, local variable block_shift is initialized to 31. If block_shift is 31, 1 << block_shift is 1 << 31 = 0x80000000=-214748368. This is the most negative int value. Inside the round_up macro, there is a cast applied to ((1 << 31) - 1). However, this cast is applied AFTER ((1 << 31) - 1) is calculated. Since (1 << 31) is treated as an int, we get the negative overflow identified by UBSAN in the process of calculating ((1 << 31) - 1). The fix is to change (1 << block_shift) to (1ULL << block_shift) on line 349. Fixes: 9901abf58368 ("IB/mlx4: Use optimal numbers of MTT entries") Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il> Signed-off-by: Leon Romanovsky <leonro@mellanox.com> Signed-off-by: Doug Ledford <dledford@redhat.com>
-rw-r--r--drivers/infiniband/hw/mlx4/mr.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/infiniband/hw/mlx4/mr.c b/drivers/infiniband/hw/mlx4/mr.c
index 17f4f151a97f..61d8b06375bb 100644
--- a/drivers/infiniband/hw/mlx4/mr.c
+++ b/drivers/infiniband/hw/mlx4/mr.c
@@ -346,7 +346,7 @@ int mlx4_ib_umem_calc_optimal_mtt_size(struct ib_umem *umem, u64 start_va,
/* Add to the first block the misalignment that it suffers from. */
total_len += (first_block_start & ((1ULL << block_shift) - 1ULL));
last_block_end = current_block_start + current_block_len;
- last_block_aligned_end = round_up(last_block_end, 1 << block_shift);
+ last_block_aligned_end = round_up(last_block_end, 1ULL << block_shift);
total_len += (last_block_aligned_end - last_block_end);
if (total_len & ((1ULL << block_shift) - 1ULL))