Use of uninitialized values

[matthiasgoergens]

When building with memory sanitizer, I am getting a lot of problems like the following:

==68141==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x7feab3c79dca in FF_2048_modmul ff_2048.c
    #1 0x7feab3c7a818 in FF_2048_ct_2w_pow (/home/matthias/incubator-milagro-crypto-c/target/default/lib/libamcl_rsa_2048.so.2+0x77818)
    #2 0x7feab3c7e0e0 in FF_2048_ct_pow_2 (/home/matthias/incubator-milagro-crypto-c/target/default/lib/libamcl_rsa_2048.so.2+0x7b0e0)
    #3 0x555bd4507b73 in main (/home/matthias/incubator-milagro-crypto-c/target/default/bin/test_ff_consistency_2048+0xb6b73)
    #4 0x7feab390628f in __libc_start_call_main /usr/src/debug/glibc/glibc/csu/../sysdeps/nptl/libc_start_call_main.h:58:16
    #5 0x7feab3906349 in __libc_start_main@GLIBC_2.2.5 /usr/src/debug/glibc/glibc/csu/../csu/libc-start.c:381:3
    #6 0x555bd4474404 in _start /build/glibc/src/glibc/csu/../sysdeps/x86_64/start.S:115

  Uninitialized value was stored to memory at
    #0 0x7feab3c0ea76 in BIG_1024_58_cmove (/home/matthias/incubator-milagro-crypto-c/target/default/lib/libamcl_rsa_2048.so.2+0xba76)

  Uninitialized value was stored to memory at
    #0 0x7feab3c0ea76 in BIG_1024_58_cmove (/home/matthias/incubator-milagro-crypto-c/target/default/lib/libamcl_rsa_2048.so.2+0xba76)

  Uninitialized value was stored to memory at
    #0 0x7feab3c0ea76 in BIG_1024_58_cmove (/home/matthias/incubator-milagro-crypto-c/target/default/lib/libamcl_rsa_2048.so.2+0xba76)

  Uninitialized value was stored to memory at
    #0 0x7feab3c0ea76 in BIG_1024_58_cmove (/home/matthias/incubator-milagro-crypto-c/target/default/lib/libamcl_rsa_2048.so.2+0xba76)

  Uninitialized value was stored to memory at
    #0 0x7feab3c0ea76 in BIG_1024_58_cmove (/home/matthias/incubator-milagro-crypto-c/target/default/lib/libamcl_rsa_2048.so.2+0xba76)

  Uninitialized value was stored to memory at
    #0 0x7feab3c0ea76 in BIG_1024_58_cmove (/home/matthias/incubator-milagro-crypto-c/target/default/lib/libamcl_rsa_2048.so.2+0xba76)

  Uninitialized value was created by an allocation of 'vla' in the stack frame of function 'FF_2048_ct_2w_pow'
    #0 0x7feab3c7a170 in FF_2048_ct_2w_pow (/home/matthias/incubator-milagro-crypto-c/target/default/lib/libamcl_rsa_2048.so.2+0x77170)

SUMMARY: MemorySanitizer: use-of-uninitialized-value ff_2048.c in FF_2048_modmul
Exiting

As far as I can tell, this specific example is caused by FF_WWW_ct_2w_pow not always initialising ws. But there are more examples in the code.