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Diffstat (limited to 'etc/DEBUG')
| -rw-r--r-- | etc/DEBUG | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/etc/DEBUG b/etc/DEBUG index cfa033d6c0c..c4f0852abb3 100644 --- a/etc/DEBUG +++ b/etc/DEBUG @@ -1007,6 +1007,28 @@ Address sanitization is incompatible with undefined-behavior sanitization, unfortunately. Address sanitization is also incompatible with the --with-dumping=unexec option of 'configure'. +*** Address poisoning/unpoisoning + +When compiled with address sanitization, Emacs will also try to mark +dead/free lisp objects as poisoned, forbidding them from being +accessed without being unpoisoned first. This adds an extra layer +of checking with objects in internal free lists, which may otherwise +evade traditional use-after-free checks. To disable this, add +'allow_user_poisoning=0' to ASAN_OPTIONS, or build Emacs with +'-DGC_ASAN_POISON_OBJECTS=0' in CFLAGS. + +While using GDB, memory addresses can be inspected by using helper +functions additionally provided by the ASan library: + + (gdb) call __asan_describe_address(ptr) + +To check whether an address range is poisoned or not, use: + + (gdb) call __asan_region_is_poisoned(ptr, 8) + +Additional functions can be found in the header +'sanitizer/asan_interface.h' in your compiler's headers directory. + ** Running Emacs under Valgrind Valgrind <https://valgrind.org/> is free software that can be useful |