[Bug 6512] New: Data corruption caused by realloc()

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=6512

           Summary: Data corruption caused by realloc()
           Product: uClibc
           Version: unspecified
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: critical
          Priority: P5
         Component: Other
        AssignedTo: unassigned at uclibc.org
        ReportedBy: sss at secomea.com
                CC: uclibc-cvs at uclibc.org
   Estimated Hours: 0.0


Created attachment 5060
  --> https://bugs.busybox.net/attachment.cgi?id=5060
Patch for realloc() data corruption

In some cases data gets corrupted by calling realloc().
This happens when the size of the original memory blob is small (*) and the new
blob is allocated at a different location.
In this case, parts of the original memory doesn't get copied but will contain
random data.

(*) Specifically, if the original size is exactly 16, 24, or 32 bytes (on
32-bit architectures).

Needless to say, memory corruption can be very hard to track down and cause all
kinds of unpredictable behavior and unreproducable errors (speaking by
experience here), so this is a critical bug.

The attached patch fixes the issue.
Note that while the patch is based on uClibc-0.9.31, the bug is still present
in current (0.9.33.2) uClibc.

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