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mmap.2: Minor wording improvements to text on MAP_FIXED hazard
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
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@ -743,12 +743,13 @@ making it easy for a multithreaded process to corrupt its own address space.
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.PP
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.PP
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For example, suppose that thread A looks through
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For example, suppose that thread A looks through
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.I /proc/<pid>/maps
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.I /proc/<pid>/maps
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and locates an available address range,
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and in order to locate an unused address range that it can map using
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.BR MAP_FIXED ,
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while thread B simultaneously acquires part or all of that same
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while thread B simultaneously acquires part or all of that same
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address range.
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address range.
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Thread A then calls
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When thread A subsequently employs
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.BR mmap(MAP_FIXED) ,
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.BR mmap(MAP_FIXED) ,
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effectively overwriting the mapping that thread B created.
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it will effectively clobber the mapping that thread B created.
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In this scenario,
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In this scenario,
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thread B need not create a mapping directly; simply making a library call
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thread B need not create a mapping directly; simply making a library call
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that, internally, uses
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that, internally, uses
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