From: Colin Ian King <redacted>

[ Upstream commit dee9d154f40c58d02f69acdaa5cfd1eae6ebc28b ]

It is possible for the call to omap_iommu_dump_ctx to return
a negative error number, so check for the failure and return
the error number rather than pass the negative value to
simple_read_from_buffer.

Fixes: 14e0e6796a0d ("OMAP: iommu: add initial debugfs support")
Signed-off-by: Colin Ian King <redacted>
Link: https://lore.kernel.org/r/20200714192211.744776-1-colin.king@canonical.com (local)
Addresses-Coverity: ("Improper use of negative value")
Signed-off-by: Joerg Roedel <redacted>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/iommu/omap-iommu-debug.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/iommu/omap-iommu-debug.c b/drivers/iommu/omap-iommu-debug.c
index 50217548c3b8e..5ce55fabc9d80 100644
--- a/drivers/iommu/omap-iommu-debug.c
+++ b/drivers/iommu/omap-iommu-debug.c

@@ -101,8 +101,11 @@ static ssize_t debug_read_regs(struct file *file, char __user *userbuf,
 	mutex_lock(&iommu_debug_lock);
 
 	bytes = omap_iommu_dump_ctx(obj, p, count);
+	if (bytes < 0)
+		goto err;
 	bytes = simple_read_from_buffer(userbuf, count, ppos, buf, bytes);
 
+err:
 	mutex_unlock(&iommu_debug_lock);
 	kfree(buf);
 

-- 
2.25.1