[Bug c/84052] Using Randomizing structure layout plugin in linux kernel compilation doesn't generate proper debuginfo
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84052 ezannoni changed: What|Removed |Added CC||ezannoni at gmail dot com --- Comment #10 from ezannoni --- Hi Andrew, do you have a pointer to the committee recommendation or discussion, it would be helpful to understand the reasoning. thanks
[Bug c/84052] Using Randomizing structure layout plugin in linux kernel compilation doesn't generate proper debuginfo
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84052 Andrew Pinski changed: What|Removed |Added Resolution|--- |WONTFIX Status|UNCONFIRMED |RESOLVED --- Comment #9 from Andrew Pinski --- Randomizing fields order is invalid thing to do in general. C++ committee even went out of its way to make a mention that it is invalid (there is a defect report asking about it). Also this is not security at all, this just makes things not reproducible at all and even if you have the same seed small changes could change things.
[Bug c/84052] Using Randomizing structure layout plugin in linux kernel compilation doesn't generate proper debuginfo
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84052 Sam James changed: What|Removed |Added CC||david.faust at oracle dot com, ||kees at outflux dot net Status|RESOLVED|UNCONFIRMED Resolution|INVALID |--- --- Comment #8 from Sam James --- Reopening per above for discussion. We've had some discussion off-bug about it as well.
[Bug c/84052] Using Randomizing structure layout plugin in linux kernel compilation doesn't generate proper debuginfo
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84052 Arsen Arsenović changed: What|Removed |Added CC||arsen at gcc dot gnu.org --- Comment #7 from Arsen Arsenović --- I think this can be fixed in the plugin if a new event was added to GCC just before laying out the struct: modified gcc/c/c-decl.cc @@ -9678,6 +9678,9 @@ finish_struct (location_t loc, tree t, tree fieldlist, tree attributes, TYPE_FIELDS (t) = fieldlist; + invoke_plugin_callbacks (PLUGIN_BEFORE_STRUCT_LAYOUT, t); + fieldlist = TYPE_FIELDS (t); + maybe_apply_pragma_scalar_storage_order (t); layout_type (t); I've modified the current Linux randomizer plugin to make use of this and it /seems/ to work but I didn't fully test it yet so I'm not sure. WDYT of the above?
[Bug c/84052] Using Randomizing structure layout plugin in linux kernel compilation doesn't generate proper debuginfo
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84052 Jordan Beaubien changed: What|Removed |Added CC||mivicaf210 at mxclip dot com --- Comment #6 from Jordan Beaubien --- This is a massive issue. https://www.plastererswollongong.com.au
[Bug c/84052] Using Randomizing structure layout plugin in linux kernel compilation doesn't generate proper debuginfo
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84052 --- Comment #5 from PaX Team --- (In reply to Andrew Pinski from comment #4) > Because debug information happens early on and has many interactions with > the front end. FINISH_TYPE happens early on too and the API promise gcc makes is that it's invoked "After finishing parsing a type" (in practice that's right after c_parser_struct_or_union_specifier for this case). clearly there's a sequencing problem between this and the emission of debug information which means it's either undocumented (gcc bug) or unintended (gcc bug). i don't know which it is but clearly something is not right.
[Bug c/84052] Using Randomizing structure layout plugin in linux kernel compilation doesn't generate proper debuginfo
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84052 --- Comment #4 from Andrew Pinski --- (In reply to Cao jin from comment #2) > (In reply to Andrew Pinski from comment #1) > > Plugins issues like this should reported to the plugin author and not to > > gcc. > > I don't know gcc internals, from my very limited understanding about gcc & > that plugin, the plugin just does one optimization on the intermediate > language: redefine a structure with randomized order and set it back to its > context. So the backend would see a structure different from its original > definition in source file and could generate the proper debuginfo. So I > feels this issue may be more close to gcc. > > I was not sure where should I report this problem. I was hoping gcc guys > could take a look at that plugin, I feel it is not hard for you gcc expert > to read, even I can tell the basic logic inside. It is not the job of gcc developers to figure out a bug in a plugin or gcc. It is plugin writer's job to do that. (In reply to PaX Team from comment #3) > (In reply to Andrew Pinski from comment #1) > > Plugins issues like this should reported to the plugin author and not to > > gcc. > what makes you think it's a plugin issue? i reported several gcc bugs myself > over the years that i ran across while developing plugins (some have yet to > be addressed fwiw). this case is no different, it's a gcc bug where > sometimes gcc emits debug info for a type that has not even been constructed > yet. Because debug information happens early on and has many interactions with the front end. Most optimizations don't change types. In fact changing of the type after the fact is not the correct approach, you need to duplication the type and then lay it out and change all of the ir. This is how struct reorg would work. Also you have to check to make sure the types don't escape. Now of that code exists in gcc right now. So again this is outside of the scope of gcc bug.
[Bug c/84052] Using Randomizing structure layout plugin in linux kernel compilation doesn't generate proper debuginfo
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84052 --- Comment #3 from PaX Team --- (In reply to Andrew Pinski from comment #1) > Plugins issues like this should reported to the plugin author and not to gcc. what makes you think it's a plugin issue? i reported several gcc bugs myself over the years that i ran across while developing plugins (some have yet to be addressed fwiw). this case is no different, it's a gcc bug where sometimes gcc emits debug info for a type that has not even been constructed yet.
[Bug c/84052] Using Randomizing structure layout plugin in linux kernel compilation doesn't generate proper debuginfo
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84052 --- Comment #2 from pino --- (In reply to Andrew Pinski from comment #1) > Plugins issues like this should reported to the plugin author and not to gcc. I don't know gcc internals, from my very limited understanding about gcc & that plugin, the plugin just does one optimization on the intermediate language: redefine a structure with randomized order and set it back to its context. So the backend would see a structure different from its original definition in source file and could generate the proper debuginfo. So I feels this issue may be more close to gcc. I was not sure where should I report this problem. I was hoping gcc guys could take a look at that plugin, I feel it is not hard for you gcc expert to read, even I can tell the basic logic inside.
[Bug c/84052] Using Randomizing structure layout plugin in linux kernel compilation doesn't generate proper debuginfo
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84052 Andrew Pinski changed: What|Removed |Added Status|UNCONFIRMED |RESOLVED Resolution|--- |INVALID --- Comment #1 from Andrew Pinski --- Plugins issues like this should reported to the plugin author and not to gcc.
