From 1a4c27355e146b6d8cc6487b998462c7fdd1048f Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Thu, 11 Apr 2019 18:12:00 -0300 Subject: elf: Fix pldd (BZ#18035) Since 9182aa67994 (Fix vDSO l_name for GDB's, BZ#387) the initial link_map for executable itself and loader will have both l_name and l_libname->name holding the same value due: elf/dl-object.c 95 new->l_name = *realname ? realname : (char *) newname->name + libname_len - 1; Since newname->name points to new->l_libname->name. This leads to pldd to an infinite call at: elf/pldd-xx.c 203 again: 204 while (1) 205 { 206 ssize_t n = pread64 (memfd, tmpbuf.data, tmpbuf.length, name_offset); 228 /* Try the l_libname element. */ 229 struct E(libname_list) ln; 230 if (pread64 (memfd, &ln, sizeof (ln), m.l_libname) == sizeof (ln)) 231 { 232 name_offset = ln.name; 233 goto again; 234 } Since the value at ln.name (l_libname->name) will be the same as previously read. The straightforward fix is just avoid the check and read the new list entry. I checked also against binaries issues with old loaders with fix for BZ#387, and pldd could dump the shared objects. Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu, and powerpc64le-linux-gnu. [BZ #18035] * elf/Makefile (tests-container): Add tst-pldd. * elf/pldd-xx.c: Use _Static_assert in of pldd_assert. (E(find_maps)): Avoid use alloca, use default read file operations instead of explicit LFS names, and fix infinite loop. * elf/pldd.c: Explicit set _FILE_OFFSET_BITS, cleanup headers. (get_process_info): Use _Static_assert instead of assert, use default directory operations instead of explicit LFS names, and free some leadek pointers. * elf/tst-pldd.c: New file. --- elf/pldd-xx.c | 114 +++++++++++++++++++++------------------------------------- 1 file changed, 40 insertions(+), 74 deletions(-) (limited to 'elf/pldd-xx.c') diff --git a/elf/pldd-xx.c b/elf/pldd-xx.c index 547f840..756f6d7 100644 --- a/elf/pldd-xx.c +++ b/elf/pldd-xx.c @@ -23,10 +23,6 @@ #define EW_(e, w, t) EW__(e, w, _##t) #define EW__(e, w, t) e##w##t -#define pldd_assert(name, exp) \ - typedef int __assert_##name[((exp) != 0) - 1] - - struct E(link_map) { EW(Addr) l_addr; @@ -39,12 +35,12 @@ struct E(link_map) EW(Addr) l_libname; }; #if CLASS == __ELF_NATIVE_CLASS -pldd_assert (l_addr, (offsetof (struct link_map, l_addr) - == offsetof (struct E(link_map), l_addr))); -pldd_assert (l_name, (offsetof (struct link_map, l_name) - == offsetof (struct E(link_map), l_name))); -pldd_assert (l_next, (offsetof (struct link_map, l_next) - == offsetof (struct E(link_map), l_next))); +_Static_assert (offsetof (struct link_map, l_addr) + == offsetof (struct E(link_map), l_addr), "l_addr"); +_Static_assert (offsetof (struct link_map, l_name) + == offsetof (struct E(link_map), l_name), "l_name"); +_Static_assert (offsetof (struct link_map, l_next) + == offsetof (struct E(link_map), l_next), "l_next"); #endif @@ -54,10 +50,10 @@ struct E(libname_list) EW(Addr) next; }; #if CLASS == __ELF_NATIVE_CLASS -pldd_assert (name, (offsetof (struct libname_list, name) - == offsetof (struct E(libname_list), name))); -pldd_assert (next, (offsetof (struct libname_list, next) - == offsetof (struct E(libname_list), next))); +_Static_assert (offsetof (struct libname_list, name) + == offsetof (struct E(libname_list), name), "name"); +_Static_assert (offsetof (struct libname_list, next) + == offsetof (struct E(libname_list), next), "next"); #endif struct E(r_debug) @@ -69,16 +65,17 @@ struct E(r_debug) EW(Addr) r_map; }; #if CLASS == __ELF_NATIVE_CLASS -pldd_assert (r_version, (offsetof (struct r_debug, r_version) - == offsetof (struct E(r_debug), r_version))); -pldd_assert (r_map, (offsetof (struct r_debug, r_map) - == offsetof (struct E(r_debug), r_map))); +_Static_assert (offsetof (struct r_debug, r_version) + == offsetof (struct E(r_debug), r_version), "r_version"); +_Static_assert (offsetof (struct r_debug, r_map) + == offsetof (struct E(r_debug), r_map), "r_map"); #endif static int -E(find_maps) (pid_t pid, void *auxv, size_t auxv_size) +E(find_maps) (const char *exe, int memfd, pid_t pid, void *auxv, + size_t auxv_size) { EW(Addr) phdr = 0; unsigned int phnum = 0; @@ -104,12 +101,9 @@ E(find_maps) (pid_t pid, void *auxv, size_t auxv_size) if (phdr == 0 || phnum == 0 || phent == 0) error (EXIT_FAILURE, 0, gettext ("cannot find program header of process")); - EW(Phdr) *p = alloca (phnum * phent); - if (pread64 (memfd, p, phnum * phent, phdr) != phnum * phent) - { - error (0, 0, gettext ("cannot read program header")); - return EXIT_FAILURE; - } + EW(Phdr) *p = xmalloc (phnum * phent); + if (pread (memfd, p, phnum * phent, phdr) != phnum * phent) + error (EXIT_FAILURE, 0, gettext ("cannot read program header")); /* Determine the load offset. We need this for interpreting the other program header entries so we do this in a separate loop. @@ -129,24 +123,18 @@ E(find_maps) (pid_t pid, void *auxv, size_t auxv_size) if (p[i].p_type == PT_DYNAMIC) { EW(Dyn) *dyn = xmalloc (p[i].p_filesz); - if (pread64 (memfd, dyn, p[i].p_filesz, offset + p[i].p_vaddr) + if (pread (memfd, dyn, p[i].p_filesz, offset + p[i].p_vaddr) != p[i].p_filesz) - { - error (0, 0, gettext ("cannot read dynamic section")); - return EXIT_FAILURE; - } + error (EXIT_FAILURE, 0, gettext ("cannot read dynamic section")); /* Search for the DT_DEBUG entry. */ for (unsigned int j = 0; j < p[i].p_filesz / sizeof (EW(Dyn)); ++j) if (dyn[j].d_tag == DT_DEBUG && dyn[j].d_un.d_ptr != 0) { struct E(r_debug) r; - if (pread64 (memfd, &r, sizeof (r), dyn[j].d_un.d_ptr) + if (pread (memfd, &r, sizeof (r), dyn[j].d_un.d_ptr) != sizeof (r)) - { - error (0, 0, gettext ("cannot read r_debug")); - return EXIT_FAILURE; - } + error (EXIT_FAILURE, 0, gettext ("cannot read r_debug")); if (r.r_map != 0) { @@ -160,13 +148,10 @@ E(find_maps) (pid_t pid, void *auxv, size_t auxv_size) } else if (p[i].p_type == PT_INTERP) { - interp = alloca (p[i].p_filesz); - if (pread64 (memfd, interp, p[i].p_filesz, offset + p[i].p_vaddr) + interp = xmalloc (p[i].p_filesz); + if (pread (memfd, interp, p[i].p_filesz, offset + p[i].p_vaddr) != p[i].p_filesz) - { - error (0, 0, gettext ("cannot read program interpreter")); - return EXIT_FAILURE; - } + error (EXIT_FAILURE, 0, gettext ("cannot read program interpreter")); } if (list == 0) @@ -174,14 +159,16 @@ E(find_maps) (pid_t pid, void *auxv, size_t auxv_size) if (interp == NULL) { // XXX check whether the executable itself is the loader - return EXIT_FAILURE; + exit (EXIT_FAILURE); } // XXX perhaps try finding ld.so and _r_debug in it - - return EXIT_FAILURE; + exit (EXIT_FAILURE); } + free (p); + free (interp); + /* Print the PID and program name first. */ printf ("%lu:\t%s\n", (unsigned long int) pid, exe); @@ -192,47 +179,27 @@ E(find_maps) (pid_t pid, void *auxv, size_t auxv_size) do { struct E(link_map) m; - if (pread64 (memfd, &m, sizeof (m), list) != sizeof (m)) - { - error (0, 0, gettext ("cannot read link map")); - status = EXIT_FAILURE; - goto out; - } + if (pread (memfd, &m, sizeof (m), list) != sizeof (m)) + error (EXIT_FAILURE, 0, gettext ("cannot read link map")); EW(Addr) name_offset = m.l_name; - again: while (1) { - ssize_t n = pread64 (memfd, tmpbuf.data, tmpbuf.length, name_offset); + ssize_t n = pread (memfd, tmpbuf.data, tmpbuf.length, name_offset); if (n == -1) - { - error (0, 0, gettext ("cannot read object name")); - status = EXIT_FAILURE; - goto out; - } + error (EXIT_FAILURE, 0, gettext ("cannot read object name")); if (memchr (tmpbuf.data, '\0', n) != NULL) break; if (!scratch_buffer_grow (&tmpbuf)) - { - error (0, 0, gettext ("cannot allocate buffer for object name")); - status = EXIT_FAILURE; - goto out; - } + error (EXIT_FAILURE, 0, + gettext ("cannot allocate buffer for object name")); } - if (((char *)tmpbuf.data)[0] == '\0' && name_offset == m.l_name - && m.l_libname != 0) - { - /* Try the l_libname element. */ - struct E(libname_list) ln; - if (pread64 (memfd, &ln, sizeof (ln), m.l_libname) == sizeof (ln)) - { - name_offset = ln.name; - goto again; - } - } + /* The m.l_name and m.l_libname.name for loader linkmap points to same + values (since BZ#387 fix). Trying to use l_libname name as the + shared object name might lead to an infinite loop (BZ#18035). */ /* Skip over the executable. */ if (((char *)tmpbuf.data)[0] != '\0') @@ -242,7 +209,6 @@ E(find_maps) (pid_t pid, void *auxv, size_t auxv_size) } while (list != 0); - out: scratch_buffer_free (&tmpbuf); return status; } -- cgit v1.1