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Date: Tue, 3 Apr 2018 13:06:09 +0000
From: "Siebenborn, Axel" <axel.siebenborn@....com>
To: "musl@...ts.openwall.com" <musl@...ts.openwall.com>
Subject: [PATCH] dl_addr: compare addr with sym->st_size.

Hi,
this patch fixes a problem with dl_addr.

We found symbols, in cases we should not find a symbol, since the comparison with sym->st_size is missing.

According to the spec, dl_addr should not return an error in this case. Instead dli_sname and dli_addr should be set to NULL.

Regards,
Axel

diff --git a/ldso/dynlink.c b/ldso/dynlink.c
index 9bf6924..cc87dc0 100644
--- a/ldso/dynlink.c
+++ b/ldso/dynlink.c
@@ -1958,7 +1958,7 @@ int dladdr(const void *addr, Dl_info *info)
                 && (1<<(sym->st_info&0xf) & OK_TYPES)
                 && (1<<(sym->st_info>>4) & OK_BINDS)) {
                        void *symaddr = laddr(p, sym->st_value);
-                       if (symaddr > addr || symaddr < best)
+                       if (symaddr > addr || (void*) ((uint8_t*) symaddr + sym->st_size) < addr || symaddr < best)
                                continue;
                        best = symaddr;
                        bestsym = sym;
@@ -1967,13 +1967,16 @@ int dladdr(const void *addr, Dl_info *info)
                }
        }
 
-       if (!best) return 0;
-
-       if (DL_FDPIC && (bestsym->st_info&0xf) == STT_FUNC)
-               best = p->funcdescs + (bestsym - p->syms);
-
        info->dli_fname = p->name;
        info->dli_fbase = p->map;
+       if (!best) {
+               info->dli_sname = 0;
+               info->dli_saddr = 0;
+               return 0
+       }
+
+       if ( DL_FDPIC && (bestsym->st_info&0xf) == STT_FUNC)
+               best = p->funcdescs + (bestsym - p->syms);
        info->dli_sname = strings + bestsym->st_name;
        info->dli_saddr = best;

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