[PATCH 1/2] stdlib: Fix unintended change to the random_r implementation

[Florian Weimer]

Commit d5bceac99d24af1131b90027dab267e437b65cd1 changed the sequence
of random numbers.  This was completely unintended.  The statistical
properties of the new sequences are unclear, so restore the old
behavior.

Fixes commit d5bceac99d24af1131b90027dab267e437b65cd1 ("stdlib:
random_r: fix unaligned access in initstate and initstate_r
[BZ #30584]").
---
 stdlib/random_r.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/stdlib/random_r.c b/stdlib/random_r.c
index 605e96983c..b49f03f5be 100644
--- a/stdlib/random_r.c
+++ b/stdlib/random_r.c
@@ -390,9 +390,10 @@ __random_r (struct random_data *buf, int32_t *result)
       int32_t *end_ptr = buf->end_ptr;
       uint32_t val;
 
-      val = read_state (rptr, 0);
-      int32_t t = read_state (fptr, 0);
-      write_state (fptr, 0, t + val);
+      /* Avoid integer overflow with uint32_t arihmetic.  */
+      val = read_state (fptr, 0);
+      val += read_state (rptr, 0);
+      write_state (fptr, 0, val);
       /* Chucking least random bit.  */
       *result = val >> 1;
       ++fptr;

base-commit: a3131e71cf65c0c28869824de9b1b1fab363882c
-- 
2.48.1