This is the mail archive of the
binutils@sourceware.org
mailing list for the binutils project.
[PATCH v4 34/35 NEW] libctf: make ctf_dump not crash on OOM
- From: Nick Alcock <nick dot alcock at oracle dot com>
- To: binutils at sourceware dot org
- Cc: Nick Alcock <nick dot alcock at oracle dot com>
- Date: Tue, 24 Sep 2019 14:51:30 +0100
- Subject: [PATCH v4 34/35 NEW] libctf: make ctf_dump not crash on OOM
- References: <20190924135131.441906-1-nick.alcock@oracle.com>
ctf_dump calls ctf_str_append extensively but never checks to see if it
returns NULL (on OOM). If it ever does, we truncate the string we are
appending to and leak it!
Instead, create a variant of ctf_str_append that returns the *original
string* on OOM, and use it in ctf-dump. It is far better to omit a tiny
piece of a dump on OOM than to omit a bigger piece, and it is also
better to do this in what is after all purely debugging code than it is
to uglify ctf-dump.c with huge numbers of checks for the out-of-memory
case. Slightly truncated debugging output is better than no debugging
output at all and an out-of-memory message.
New in v4.
libctf/
* ctf-impl.h (ctf_str_append_noerr): Declare.
* ctf-util.c (ctf_str_append_noerr): Define in terms of
ctf_str_append.
* ctf-dump.c (str_append): New, call it.
(ctf_dump_format_type): Use str_append, not ctf_str_append.
(ctf_dump_label): Likewise.
(ctf_dump_objts): Likewise.
(ctf_dump_funcs): Likewise.
(ctf_dump_var): Likewise.
(ctf_dump_member): Likewise.
(ctf_dump_type): Likewise.
(ctf_dump): Likewise.
---
libctf/ctf-dump.c | 53 +++++++++++++++++++++++++++--------------------
libctf/ctf-impl.h | 1 +
libctf/ctf-util.c | 15 +++++++++++++-
3 files changed, 46 insertions(+), 23 deletions(-)
diff --git a/libctf/ctf-dump.c b/libctf/ctf-dump.c
index 4478edc2bee..4b05b7e8793 100644
--- a/libctf/ctf-dump.c
+++ b/libctf/ctf-dump.c
@@ -20,6 +20,8 @@
#include <ctf-impl.h>
#include <string.h>
+#define str_append(s, a) ctf_str_append_noerr (s, a)
+
/* One item to be dumped, in string form. */
typedef struct ctf_dump_item
@@ -119,7 +121,7 @@ ctf_dump_format_type (ctf_file_t *fp, ctf_id_t id, int flag)
{
if (id == 0 || ctf_errno (fp) == ECTF_NONREPRESENTABLE)
{
- str = ctf_str_append (str, " (type not represented in CTF)");
+ str = str_append (str, " (type not represented in CTF)");
ctf_set_errno (fp, ECTF_NOTREF);
break;
}
@@ -147,13 +149,13 @@ ctf_dump_format_type (ctf_file_t *fp, ctf_id_t id, int flag)
}
free (buf);
buf = NULL;
- str = ctf_str_append (str, bit);
+ str = str_append (str, bit);
free (bit);
bit = NULL;
new_id = ctf_type_reference (fp, id);
if (new_id != CTF_ERR)
- str = ctf_str_append (str, " ->");
+ str = str_append (str, " ->");
} while (new_id != CTF_ERR);
if (ctf_errno (fp) != ECTF_NOTREF)
@@ -319,7 +321,7 @@ ctf_dump_label (const char *name, const ctf_lblinfo_t *info,
return -1; /* errno is set for us. */
}
- str = ctf_str_append (str, typestr);
+ str = str_append (str, typestr);
free (typestr);
ctf_dump_append (state, str);
@@ -376,7 +378,7 @@ ctf_dump_objts (ctf_file_t *fp, ctf_dump_state_t *state)
return -1; /* errno is set for us. */
}
- str = ctf_str_append (str, typestr);
+ str = str_append (str, typestr);
free (typestr);
ctf_dump_append (state, str);
@@ -426,7 +428,7 @@ ctf_dump_funcs (ctf_file_t *fp, ctf_dump_state_t *state)
goto err;
}
- str = ctf_str_append (str, " ");
+ str = str_append (str, " ");
/* Function name. */
@@ -441,8 +443,8 @@ ctf_dump_funcs (ctf_file_t *fp, ctf_dump_state_t *state)
if (asprintf (&bit, "%s (0x%lx) ", sym_name, (unsigned long) i) < 0)
goto oom;
}
- str = ctf_str_append (str, bit);
- str = ctf_str_append (str, " (");
+ str = str_append (str, bit);
+ str = str_append (str, " (");
free (bit);
/* Function arguments. */
@@ -460,15 +462,15 @@ ctf_dump_funcs (ctf_file_t *fp, ctf_dump_state_t *state)
err = "look up argument type name";
goto err;
}
- str = ctf_str_append (str, bit);
+ str = str_append (str, bit);
if ((j < fi.ctc_argc - 1) || (fi.ctc_flags & CTF_FUNC_VARARG))
- str = ctf_str_append (str, ", ");
+ str = str_append (str, ", ");
free (bit);
}
if (fi.ctc_flags & CTF_FUNC_VARARG)
- str = ctf_str_append (str, "...");
- str = ctf_str_append (str, ")");
+ str = str_append (str, "...");
+ str = str_append (str, ")");
free (args);
ctf_dump_append (state, str);
@@ -507,7 +509,7 @@ ctf_dump_var (const char *name, ctf_id_t type, void *arg)
return -1; /* errno is set for us. */
}
- str = ctf_str_append (str, typestr);
+ str = str_append (str, typestr);
free (typestr);
ctf_dump_append (state, str);
@@ -526,7 +528,7 @@ ctf_dump_member (const char *name, ctf_id_t id, unsigned long offset,
ssize_t i;
for (i = 0; i < depth; i++)
- *state->cdm_str = ctf_str_append (*state->cdm_str, " ");
+ *state->cdm_str = str_append (*state->cdm_str, " ");
if ((typestr = ctf_type_aname (state->cdm_fp, id)) == NULL)
{
@@ -536,7 +538,7 @@ ctf_dump_member (const char *name, ctf_id_t id, unsigned long offset,
offset) < 0)
goto oom;
- *state->cdm_str = ctf_str_append (*state->cdm_str, bit);
+ *state->cdm_str = str_append (*state->cdm_str, bit);
free (typestr);
free (bit);
return 0;
@@ -549,7 +551,7 @@ ctf_dump_member (const char *name, ctf_id_t id, unsigned long offset,
offset, id, ctf_type_kind (state->cdm_fp, id), typestr, name,
(unsigned long) ctf_type_align (state->cdm_fp, id)) < 0)
goto oom;
- *state->cdm_str = ctf_str_append (*state->cdm_str, bit);
+ *state->cdm_str = str_append (*state->cdm_str, bit);
free (typestr);
free (bit);
typestr = NULL;
@@ -563,12 +565,12 @@ ctf_dump_member (const char *name, ctf_id_t id, unsigned long offset,
if (asprintf (&bit, ", format 0x%x, offset:bits 0x%x:0x%x", ep.cte_format,
ep.cte_offset, ep.cte_bits) < 0)
goto oom;
- *state->cdm_str = ctf_str_append (*state->cdm_str, bit);
+ *state->cdm_str = str_append (*state->cdm_str, bit);
free (bit);
bit = NULL;
}
- *state->cdm_str = ctf_str_append (*state->cdm_str, ")\n");
+ *state->cdm_str = str_append (*state->cdm_str, ")\n");
return 0;
oom:
@@ -593,7 +595,7 @@ ctf_dump_type (ctf_id_t id, int flag, void *arg)
goto err;
}
- str = ctf_str_append (str, "\n");
+ str = str_append (str, "\n");
if ((ctf_type_visit (state->cds_fp, id, ctf_dump_member, &membstate)) < 0)
{
if (id == 0 || ctf_errno (state->cds_fp) == ECTF_NONREPRESENTABLE)
@@ -752,8 +754,8 @@ ctf_dump (ctf_file_t *fp, ctf_dump_state_t **statep, ctf_sect_names_t sect,
nline[0] = '\0';
ret = func (sect, line, arg);
- str = ctf_str_append (str, ret);
- str = ctf_str_append (str, "\n");
+ str = str_append (str, ret);
+ str = str_append (str, "\n");
if (ret != line)
free (ret);
@@ -772,7 +774,14 @@ ctf_dump (ctf_file_t *fp, ctf_dump_state_t **statep, ctf_sect_names_t sect,
str[len-1] = '\0';
}
else
- str = strdup (state->cds_current->cdi_item);
+ {
+ str = strdup (state->cds_current->cdi_item);
+ if (!str)
+ {
+ ctf_set_errno (fp, ENOMEM);
+ return str;
+ }
+ }
ctf_set_errno (fp, 0);
return str;
diff --git a/libctf/ctf-impl.h b/libctf/ctf-impl.h
index 0485b976192..0313f151377 100644
--- a/libctf/ctf-impl.h
+++ b/libctf/ctf-impl.h
@@ -457,6 +457,7 @@ extern ssize_t ctf_pread (int fd, void *buf, ssize_t count, off_t offset);
extern void *ctf_realloc (ctf_file_t *, void *, size_t);
extern char *ctf_str_append (char *, const char *);
+extern char *ctf_str_append_noerr (char *, const char *);
extern const char *ctf_strerror (int);
extern ctf_id_t ctf_type_resolve_unsliced (ctf_file_t *, ctf_id_t);
diff --git a/libctf/ctf-util.c b/libctf/ctf-util.c
index d10b2b53a9c..d4a1c5aaeac 100644
--- a/libctf/ctf-util.c
+++ b/libctf/ctf-util.c
@@ -103,7 +103,7 @@ ctf_sym_to_elf64 (const Elf32_Sym *src, Elf64_Sym *dst)
return dst;
}
-/* A string appender working on dynamic strings. */
+/* A string appender working on dynamic strings. Returns NULL on OOM. */
char *
ctf_str_append (char *s, const char *append)
@@ -127,6 +127,19 @@ ctf_str_append (char *s, const char *append)
return s;
}
+/* A version of ctf_str_append that returns the old string on OOM. */
+
+char *
+ctf_str_append_noerr (char *s, const char *append)
+{
+ char *new_s;
+
+ new_s = ctf_str_append (s, append);
+ if (!new_s)
+ return s;
+ return new_s;
+}
+
/* A realloc() that fails noisily if called with any ctf_str_num_users. */
void *
ctf_realloc (ctf_file_t *fp, void *ptr, size_t size)
--
2.23.0.239.g28aa4420fd