[glibc] elf: Fix failure handling in _dl_map_object_from_fd
Szabolcs Nagy
nsz@sourceware.org
Tue Dec 15 11:47:57 GMT 2020
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=c6b016532705e158a330c31697e9dd4826aa68af
commit c6b016532705e158a330c31697e9dd4826aa68af
Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date: Tue Nov 24 12:34:39 2020 +0000
elf: Fix failure handling in _dl_map_object_from_fd
The failure paths in _dl_map_object_from_fd did not clean every
potentially allocated resource up.
Handle l_phdr, l_libname and mapped segments in the common failure
handling code.
There are various bits that may not be cleaned properly on failure
(e.g. executable stack, incomplete dl_map_segments) fixing those
need further changes.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Diff:
---
elf/dl-load.c | 25 +++++++++++++++----------
1 file changed, 15 insertions(+), 10 deletions(-)
diff --git a/elf/dl-load.c b/elf/dl-load.c
index b1865a17d5..21c2920396 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -955,8 +955,14 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd,
/* The file might already be closed. */
if (fd != -1)
__close_nocancel (fd);
+ if (l != NULL && l->l_map_start != 0)
+ _dl_unmap_segments (l);
if (l != NULL && l->l_origin != (char *) -1l)
free ((char *) l->l_origin);
+ if (l != NULL && !l->l_libname->dont_free)
+ free (l->l_libname);
+ if (l != NULL && l->l_phdr_allocated)
+ free ((void *) l->l_phdr);
free (l);
free (realname);
@@ -1251,7 +1257,11 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd,
errstring = _dl_map_segments (l, fd, header, type, loadcmds, nloadcmds,
maplength, has_holes, loader);
if (__glibc_unlikely (errstring != NULL))
- goto lose;
+ {
+ /* Mappings can be in an inconsistent state: avoid unmap. */
+ l->l_map_start = l->l_map_end = 0;
+ goto lose;
+ }
}
if (l->l_ld == 0)
@@ -1274,15 +1284,6 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd,
|| (__glibc_unlikely (l->l_flags_1 & DF_1_PIE)
&& __glibc_unlikely ((mode & __RTLD_OPENEXEC) == 0)))
{
- /* We are not supposed to load this object. Free all resources. */
- _dl_unmap_segments (l);
-
- if (!l->l_libname->dont_free)
- free (l->l_libname);
-
- if (l->l_phdr_allocated)
- free ((void *) l->l_phdr);
-
if (l->l_flags_1 & DF_1_PIE)
errstring
= N_("cannot dynamically load position-independent executable");
@@ -1387,6 +1388,10 @@ cannot enable executable stack as shared object requires");
/* Signal that we closed the file. */
fd = -1;
+ /* Failures before this point are handled locally via lose.
+ There are no more failures in this function until return,
+ to change that the cleanup handling needs to be updated. */
+
/* If this is ET_EXEC, we should have loaded it as lt_executable. */
assert (type != ET_EXEC || l->l_type == lt_executable);
More information about the Glibc-cvs
mailing list