iommu/omap: Fix buffer overflow in debugfs

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: iommu/omap: Fix buffer overflow in debugfs There are two issues here: 1) The "len" variable needs to be checked before the very first write. Otherwise if omap2_iommu_dump_ctx() with "bytes" less than 32 it is a buffer overflow. 2) The snprintf() function returns the number of bytes that *would* have been copied if there were enough space. But we want to know the number of bytes which were *actually* copied so use scnprintf() instead.

References

• https://git.kernel.org/stable/c/706e359cf046c142db290244c3f4938b20fbe805
• https://git.kernel.org/stable/c/ec53b99b6b9da8b501f001595a6260c03b42d5b7
• https://git.kernel.org/stable/c/648472df221f2bbffb433b964bcb87baccc586d8
• https://git.kernel.org/stable/c/4010a1afaae1c0fb9c2cac5de703bed29b1f1782
• https://git.kernel.org/stable/c/2fee0dbfaeaaa4bda04279ce772c4572b1429d04
• https://git.kernel.org/stable/c/0c7043a5b5c3b35f5dc8875757f71e7f491d64d4
• https://git.kernel.org/stable/c/bd0438f534b2e31b12f0b39b355c5dc2bbdaf854
• https://git.kernel.org/stable/c/9814cc350e0765ce69244bf55ae4c8b29facd27e
• https://git.kernel.org/stable/c/184233a5202786b20220acd2d04ddf909ef18f29