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| author | Artem Savkov <asavkov@redhat.com> | 2018-11-20 11:52:16 -0600 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-12-17 09:28:50 +0100 |
| commit | 5ce4164fff6735d7f26b3e465deb7133cea558e9 (patch) | |
| tree | 892223e5ea63e75ca726a193e6ab92ddde9c03a8 | |
| parent | de21975e71fe3fbb96b42fe6155d8a74fc74e4ca (diff) | |
| download | linux-stable-5ce4164fff6735d7f26b3e465deb7133cea558e9.tar.gz linux-stable-5ce4164fff6735d7f26b3e465deb7133cea558e9.tar.bz2 linux-stable-5ce4164fff6735d7f26b3e465deb7133cea558e9.zip | |
objtool: Fix segfault in .cold detection with -ffunction-sections
[ Upstream commit 22566c1603030f0a036ad564634b064ad1a55db2 ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | tools/objtool/elf.c | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c index 3616d626991e..dd4ed7c3c062 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) continue; sym->pfunc = sym->cfunc = sym; @@ -305,9 +309,16 @@ static int read_symbols(struct elf *elf) if (!coldstr) continue; - 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", |