https://sourceware.org/bugzilla/show_bug.cgi?id=26921
Bug ID: 26921
Summary: dwarf_getalt () not thread-safe
Product: elfutils
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: libdw
Assignee: unassigned at sourceware dot org
Reporter: mark at klomp dot org
CC: elfutils-devel at sourceware dot org
Target Milestone: ---
When walking a DIE tree getting any attribute values that come from an alt file
(or DWARF5 supplemental file) is not thread-safe. The dwarf_getalt () function
does the following (without any locking):
Dwarf *
dwarf_getalt (Dwarf *main)
{
/* Only try once. */
if (main == NULL || main->alt_dwarf == (void *) -1)
return NULL;
if (main->alt_dwarf != NULL)
return main->alt_dwarf;
find_debug_altlink (main);
/* If we found nothing, make sure we don't try again. */
if (main->alt_dwarf == NULL)
{
main->alt_dwarf = (void *) -1;
return NULL;
}
return main->alt_dwarf;
}
find_debug_altlink will search for the alt file (which is a normal ELF file,
that will be opened with dwarf_begin) if it can be found (and no error occurs).
The rest of the code (except for dwarf_end and an explicit dwarf_setalt call)
doesn't access dwarf->alt_dwarf directly, but all call dwarf_getalt to access
it.
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