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[msan] Don't unpoison phdrs on dlopen(NULL, 0)
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Authored by rnk on Nov 18 2015, 4:32 PM.

Details

Summary

dlopen(NULL, ...) is intended to give you back a handle to the
executable for use with dlsym. Casting it to link_map and using it with
ForEachMappedRegion results in a crash.

We also shouldn't unpoison the globals of a DSO that is already in
memory. This ensures that we don't do it for the executable, but in
general, MSan may have false positives if the DSO is already loaded.

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rL LLVM

Event Timeline

rnk updated this revision to Diff 40577.Nov 18 2015, 4:32 PM
rnk retitled this revision from to [msan] Don't unpoison phdrs on dlopen(NULL, 0).
rnk updated this object.
rnk added a reviewer: eugenis.
rnk added a subscriber: llvm-commits.
eugenis accepted this revision.Nov 18 2015, 4:49 PM
eugenis edited edge metadata.

Did you mean "false negatives if the DSO is already loaded." ?
LGTM

This revision is now accepted and ready to land.Nov 18 2015, 4:49 PM
rnk added a comment.Nov 18 2015, 4:56 PM

Ah, yeah, false negatives. Thanks!

rnk added a comment.Nov 18 2015, 4:56 PM

By the way, this fixes all the JIT crashes on the msan LLVM bot.

This revision was automatically updated to reflect the committed changes.
In D14795#292323, @rnk wrote:

By the way, this fixes all the JIT crashes on the msan LLVM bot.

This is great. Thanks for working on this.