From: Mark Winterrowd <markwinterrowd4@gmail.com>
To: musl@lists.openwall.com
Subject: Possible out of bounds memory write in initialization of xdigits in src/stdio/vfprintf.c
Date: Thu, 28 Jun 2018 10:31:55 -0700 [thread overview]
Message-ID: <CANravCDuLFZ8tV56ZKo7BpwiKS59a1nSOyuGL1-a9Pis7ZrhxQ@mail.gmail.com> (raw)
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Hi all,
On line 148 of src/stdio/vfprintf.c in the source tree head, you can
observe the following global initialization:
static const char xdigits[16] = {
"0123456789ABCDEF"
};
Note that while this xdigits array has a length of 16, the string it is
being initialized to has a length of 17, due to the implicit null
terminator. Thus, an additional '\0' will be written just past the end of
this global. I believe this could cause unpredictable effects depending
upon how the compiler and linker handle this situation.
The fix is simple, just write out a list of comma separated characters to
eliminate the null terminator or make xdigits have a length of 17.
Thanks,
Mark Winterrowd
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next reply other threads:[~2018-06-28 17:31 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-28 17:31 Mark Winterrowd [this message]
2018-06-28 17:48 ` Rich Felker
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