| Message ID | 20231115041653.810045-1-masahiroy@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | kconfig: fix memory leak from range properties | expand |
Masahiro Yamada <masahiroy@kernel.org> writes: > Currently, sym_validate_range() duplicates the range string using > xstrdup(), which is overwritten by a subsequent sym_calc_value() call. > It results in a memory leak. > > [After] > > LEAK SUMMARY: > definitely lost: 0 bytes in 0 blocks > indirectly lost: 0 bytes in 0 blocks > possibly lost: 0 bytes in 0 blocks > still reachable: 17,462 bytes in 20 blocks > suppressed: 0 bytes in 0 blocks FYI, there are quite a few other memory leaks in Kconfig (as evident from the still reachable value in the above report). I believe I've fixed most of them in this commit: https://github.com/build2-packaging/kconfig/commit/cd9910e3636515b2980ce1d37d1984ccfd6b4cb9 In particular, I could load the Linux kernel configuration repeatedly in a loop without causing any memory leaks or crashes (which were common due to the state not being reset properly). I believe the above commit also includes a fix for the sym_validate_range() leak in question, though the way it's fixed is different. The potential problem with the proposed fix is that it may be impossible to decide who should free the shared value.
diff --git a/scripts/kconfig/symbol.c b/scripts/kconfig/symbol.c index 0572330bf8a7..a76925b46ce6 100644 --- a/scripts/kconfig/symbol.c +++ b/scripts/kconfig/symbol.c @@ -122,9 +122,9 @@ static long long sym_get_range_val(struct symbol *sym, int base) static void sym_validate_range(struct symbol *sym) { struct property *prop; + struct symbol *range_sym; int base; long long val, val2; - char str[64]; switch (sym->type) { case S_INT: @@ -140,17 +140,15 @@ static void sym_validate_range(struct symbol *sym) if (!prop) return; val = strtoll(sym->curr.val, NULL, base); - val2 = sym_get_range_val(prop->expr->left.sym, base); + range_sym = prop->expr->left.sym; + val2 = sym_get_range_val(range_sym, base); if (val >= val2) { - val2 = sym_get_range_val(prop->expr->right.sym, base); + range_sym = prop->expr->right.sym; + val2 = sym_get_range_val(range_sym, base); if (val <= val2) return; } - if (sym->type == S_INT) - sprintf(str, "%lld", val2); - else - sprintf(str, "0x%llx", val2); - sym->curr.val = xstrdup(str); + sym->curr.val = range_sym->curr.val; } static void sym_set_changed(struct symbol *sym)
Currently, sym_validate_range() duplicates the range string using xstrdup(), which is overwritten by a subsequent sym_calc_value() call. It results in a memory leak. Instead, only the pointer should be copied. Below is a test case, with a summary from Valgrind. [Test Kconfig] config FOO int "foo" range 10 20 [Test .config] CONFIG_FOO=0 [Before] LEAK SUMMARY: definitely lost: 3 bytes in 1 blocks indirectly lost: 0 bytes in 0 blocks possibly lost: 0 bytes in 0 blocks still reachable: 17,465 bytes in 21 blocks suppressed: 0 bytes in 0 blocks [After] LEAK SUMMARY: definitely lost: 0 bytes in 0 blocks indirectly lost: 0 bytes in 0 blocks possibly lost: 0 bytes in 0 blocks still reachable: 17,462 bytes in 20 blocks suppressed: 0 bytes in 0 blocks Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> --- scripts/kconfig/symbol.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-)