Comment 0 for bug 1865032

Description: zipl/libc: Fix potential buffer overflow in printf
Symptom: Crash of the zipl boot loader during boot.
Problem: The zipl boot loaders have their own minimalistic libc
               implementation. In it printf and sprintf use vsprintf for string
               formatting. Per definition vsprintf assumes that the buffer it
               writes to is large enough to contain the formatted string and
               performs no size checks. This is problematic for the boot
               loaders because the buffer they use are often allocated on the
               stack. Thus even small changes to the string format can
               potentially cause buffer overflows on the stack.

Solution: Implement vsnprintf and make use of it.

Reproduction: Use printf to print a string with >81 characters (exact number
               depends on the stack layout/compiler used).

Upstream commit(s) for s390-tools:
6fe9e6c55c69c14971dca55551009f5060418aae
8874b908254c47c8a6fd7a1aca2c7371c11035c4
f7430027b41d5ad6220e962a179c2a5213330a44
36fed0e6c6590631c4ce1707c8fe3c3397bcce4d

Problem was introduced with version 1.24. Therefore these patches need to be applied to all distros in service.