From 8b8fb7f03721c42445f982582f462144ab60a1a0 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Wed, 27 Jun 2018 15:32:09 -0400 Subject: [PATCH] correctly handle non-matching symbols in dladdr based on patch by Axel Siebenborn, with fixes discussed on the mailing list after submission and and rebased around the UB fix in commit e829695fcc880f8578c2b964ea2d090f0016c9d7. avoid spurious symbol matches by dladdr beyond symbol size. for symbols with a size recorded, only match if the queried address lies within the address range determined by the symbol address and size. for symbols with no size recorded, the old closest-match behavior is kept, as long as there is no intervening symbol with a recorded size. the case where no symbol is matched, but the address does lie within the memory range of a shared object, is specified as success. fix the return value and produce a valid (with null dli_sname and dli_saddr) Dl_info structure. --- ldso/dynlink.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/ldso/dynlink.c b/ldso/dynlink.c index 6b05b5e0..31c50609 100644 --- a/ldso/dynlink.c +++ b/ldso/dynlink.c @@ -1978,6 +1978,11 @@ int dladdr(const void *addr_arg, Dl_info *info) size_t symaddr = (size_t)laddr(p, sym->st_value); if (symaddr > addr || symaddr < best) continue; + if (sym->st_size && symaddr+sym->st_size <= addr) { + best = 0; + bestsym = 0; + continue; + } best = symaddr; bestsym = sym; if (addr == symaddr) @@ -1985,13 +1990,17 @@ int dladdr(const void *addr_arg, Dl_info *info) } } - if (!best) return 0; + info->dli_fname = p->name; + info->dli_fbase = p->map; + + if (!best) { + info->dli_sname = 0; + info->dli_saddr = 0; + return 1; + } if (DL_FDPIC && (bestsym->st_info&0xf) == STT_FUNC) best = (size_t)(p->funcdescs + (bestsym - p->syms)); - - info->dli_fname = p->name; - info->dli_fbase = p->map; info->dli_sname = strings + bestsym->st_name; info->dli_saddr = (void *)best; -- 2.25.1