path: root/tools
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authorArtem Savkov <asavkov@redhat.com>2018-11-20 11:52:16 -0600
committerIngo Molnar <mingo@kernel.org>2018-11-20 18:59:00 +0100
commit22566c1603030f0a036ad564634b064ad1a55db2 (patch)
tree9822e12613667fed8bce1b66e6cca24192c710e5 /tools
parentobjtool: Fix double-free in .cold detection error path (diff)
objtool: Fix segfault in .cold detection with -ffunction-sections
Because find_symbol_by_name() traverses the same lists as read_symbols(), changing sym->name in place without copying it affects the result of find_symbol_by_name(). In the case where a ".cold" function precedes its parent in sec->symbol_list, it can result in a function being considered a parent of itself. This leads to function length being set to 0 and other consequent side-effects including a segfault in add_switch_table(). The effects of this bug are only visible when building with -ffunction-sections in KCFLAGS. Fix by copying the search string instead of modifying it in place. Signed-off-by: Artem Savkov <asavkov@redhat.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: 13810435b9a7 ("objtool: Support GCC 8's cold subfunctions") Link: http://lkml.kernel.org/r/910abd6b5a4945130fd44f787c24e07b9e07c8da.1542736240.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'tools')
1 files changed, 14 insertions, 3 deletions
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index e7a7ac40e045..b8f3cca8e58b 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -31,6 +31,8 @@
#include "elf.h"
#include "warn.h"
+#define MAX_NAME_LEN 128
struct section *find_section_by_name(struct elf *elf, const char *name)
struct section *sec;
@@ -298,6 +300,8 @@ static int read_symbols(struct elf *elf)
/* Create parent/child links for any cold subfunctions */
list_for_each_entry(sec, &elf->sections, list) {
list_for_each_entry(sym, &sec->symbol_list, list) {
+ char pname[MAX_NAME_LEN + 1];
+ size_t pnamelen;
if (sym->type != STT_FUNC)
sym->pfunc = sym->cfunc = sym;
@@ -305,9 +309,16 @@ static int read_symbols(struct elf *elf)
if (!coldstr)
- coldstr[0] = '\0';
- pfunc = find_symbol_by_name(elf, sym->name);
- coldstr[0] = '.';
+ pnamelen = coldstr - sym->name;
+ if (pnamelen > MAX_NAME_LEN) {
+ WARN("%s(): parent function name exceeds maximum length of %d characters",
+ sym->name, MAX_NAME_LEN);
+ return -1;
+ }
+ strncpy(pname, sym->name, pnamelen);
+ pname[pnamelen] = '\0';
+ pfunc = find_symbol_by_name(elf, pname);
if (!pfunc) {
WARN("%s(): can't find parent function",