Fix: leak of lttng_elf_shdr in lttng-elf.c

Most lttng_elf_shdr uses in lttng-elf.c end-up leaking the header.
Since those headers instances are always short-lived and relatively
small, these leaks are fixed by not using dynamic allocations and
instead using automatic storage.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

diff --git a/src/common/lttng-elf.c b/src/common/lttng-elf.c
index cd10632ce46bbe6f9364d31d39aa15570be7fbaf..b2aa88487e1dff286c21d0442f6cdf175a68681f 100644 (file)
--- a/src/common/lttng-elf.c
+++ b/src/common/lttng-elf.c
@@ -309,38 +309,32 @@ error:
  * Retrieve the nth (where n is the `index` argument) shdr (section
  * header) from the given elf instance.
  *
- * A pointer to the shdr is returned on success, NULL on failure.
+ * 0 is returned on succes, -1 on failure.
  */
 static
-struct lttng_elf_shdr *lttng_elf_get_section_hdr(struct lttng_elf *elf,
-               uint16_t index)
+int lttng_elf_get_section_hdr(struct lttng_elf *elf,
+               uint16_t index, struct lttng_elf_shdr *out_header)
 {
-       struct lttng_elf_shdr *section_header = NULL;
        int ret = 0;
 
        if (!elf) {
+               ret = -1;
                goto error;
        }
 
        if (index >= elf->ehdr->e_shnum) {
+               ret = -1;
                goto error;
        }
 
-       section_header = zmalloc(sizeof(struct lttng_elf_shdr));
-       if (!section_header) {
-               goto error;
-       }
-
-       ret = populate_section_header(elf, section_header, index);
+       ret = populate_section_header(elf, out_header, index);
        if (ret) {
                DBG("Error populating section header.");
                goto error;
        }
-       return section_header;
 
 error:
-       free(section_header);
-       return NULL;
+       return ret;
 }
 
 /*
@@ -534,7 +528,7 @@ end:
 static
 struct lttng_elf *lttng_elf_create(int fd)
 {
-       struct lttng_elf_shdr *section_names_shdr;
+       struct lttng_elf_shdr section_names_shdr;
        struct lttng_elf *elf = NULL;
        int ret;
 
@@ -559,15 +553,14 @@ struct lttng_elf *lttng_elf_create(int fd)
                goto error;
        }
 
-       section_names_shdr = lttng_elf_get_section_hdr(elf, elf->ehdr->e_shstrndx);
-       if (!section_names_shdr) {
+       ret = lttng_elf_get_section_hdr(
+                       elf, elf->ehdr->e_shstrndx, &section_names_shdr);
+       if (ret) {
                goto error;
        }
 
-       elf->section_names_offset = section_names_shdr->sh_offset;
-       elf->section_names_size = section_names_shdr->sh_size;
-
-       free(section_names_shdr);
+       elf->section_names_offset = section_names_shdr.sh_offset;
+       elf->section_names_size = section_names_shdr.sh_size;
        return elf;
 
 error:
@@ -606,15 +599,19 @@ void lttng_elf_destroy(struct lttng_elf *elf)
 
 static
 int lttng_elf_get_section_hdr_by_name(struct lttng_elf *elf,
-               const char *section_name, struct lttng_elf_shdr **section_hdr)
+               const char *section_name, struct lttng_elf_shdr *section_hdr)
 {
        int i;
        char *curr_section_name;
+
        for (i = 0; i < elf->ehdr->e_shnum; ++i) {
-               *section_hdr = lttng_elf_get_section_hdr(elf, i);
-               curr_section_name = lttng_elf_get_section_name(elf,
-                               (*section_hdr)->sh_name);
+               int ret = lttng_elf_get_section_hdr(elf, i, section_hdr);
 
+               if (ret) {
+                       break;
+               }
+               curr_section_name = lttng_elf_get_section_name(elf,
+                               section_hdr->sh_name);
                if (!curr_section_name) {
                        continue;
                }
@@ -678,7 +675,7 @@ int lttng_elf_convert_addr_in_text_to_offset(struct lttng_elf *elf_handle,
        off_t text_section_addr_beg;
        off_t text_section_addr_end;
        off_t offset_in_section;
-       struct lttng_elf_shdr *text_section_hdr = NULL;
+       struct lttng_elf_shdr text_section_hdr;
 
        if (!elf_handle) {
                DBG("Invalid ELF handle.");
@@ -695,9 +692,10 @@ int lttng_elf_convert_addr_in_text_to_offset(struct lttng_elf *elf_handle,
                goto error;
        }
 
-       text_section_offset = text_section_hdr->sh_offset;
-       text_section_addr_beg = text_section_hdr->sh_addr;
-       text_section_addr_end = text_section_addr_beg + text_section_hdr->sh_size;
+       text_section_offset = text_section_hdr.sh_offset;
+       text_section_addr_beg = text_section_hdr.sh_addr;
+       text_section_addr_end =
+                       text_section_addr_beg + text_section_hdr.sh_size;
 
        /*
         * Verify that the address is within the .text section boundaries.
@@ -739,8 +737,8 @@ int lttng_elf_get_symbol_offset(int fd, char *symbol, uint64_t *offset)
        char *symbol_table_data = NULL;
        char *string_table_data = NULL;
        char *string_table_name = NULL;
-       struct lttng_elf_shdr *symtab_hdr = NULL;
-       struct lttng_elf_shdr *strtab_hdr = NULL;
+       struct lttng_elf_shdr symtab_hdr;
+       struct lttng_elf_shdr strtab_hdr;
        struct lttng_elf *elf = NULL;
 
        if (!symbol || !offset ) {
@@ -778,7 +776,7 @@ int lttng_elf_get_symbol_offset(int fd, char *symbol, uint64_t *offset)
        }
 
        /* Get the data associated with the symbol table section. */
-       symbol_table_data = lttng_elf_get_section_data(elf, symtab_hdr);
+       symbol_table_data = lttng_elf_get_section_data(elf, &symtab_hdr);
        if (symbol_table_data == NULL) {
                DBG("Cannot get ELF Symbol Table data.");
                ret = LTTNG_ERR_ELF_PARSING;
@@ -794,7 +792,7 @@ int lttng_elf_get_symbol_offset(int fd, char *symbol, uint64_t *offset)
        }
 
        /* Get the data associated with the string table section. */
-       string_table_data = lttng_elf_get_section_data(elf, strtab_hdr);
+       string_table_data = lttng_elf_get_section_data(elf, &strtab_hdr);
        if (string_table_data == NULL) {
                DBG("Cannot get ELF string table section data.");
                ret = LTTNG_ERR_ELF_PARSING;
@@ -802,7 +800,7 @@ int lttng_elf_get_symbol_offset(int fd, char *symbol, uint64_t *offset)
        }
 
        /* Get the number of symbol in the table for the iteration. */
-       sym_count = symtab_hdr->sh_size / symtab_hdr->sh_entsize;
+       sym_count = symtab_hdr.sh_size / symtab_hdr.sh_entsize;
 
        /* Loop over all symbol. */
        for (sym_idx = 0; sym_idx < sym_count; sym_idx++) {
@@ -888,7 +886,7 @@ int lttng_elf_get_sdt_probe_offsets(int fd, const char *provider_name,
                const char *probe_name, uint64_t **offsets, uint32_t *nb_probes)
 {
        int ret = 0, nb_match = 0;
-       struct lttng_elf_shdr *stap_note_section_hdr = NULL;
+       struct lttng_elf_shdr stap_note_section_hdr;
        struct lttng_elf *elf = NULL;
        char *stap_note_section_data = NULL;
        char *curr_note_section_begin, *curr_data_ptr, *curr_probe, *curr_provider;
@@ -919,7 +917,8 @@ int lttng_elf_get_sdt_probe_offsets(int fd, const char *provider_name,
        }
 
        /* Get the data associated with the stap note section. */
-       stap_note_section_data = lttng_elf_get_section_data(elf, stap_note_section_hdr);
+       stap_note_section_data =
+                       lttng_elf_get_section_data(elf, &stap_note_section_hdr);
        if (stap_note_section_data == NULL) {
                DBG("Cannot get ELF stap note section data.");
                ret = LTTNG_ERR_ELF_PARSING;
@@ -934,7 +933,8 @@ int lttng_elf_get_sdt_probe_offsets(int fd, const char *provider_name,
                curr_data_ptr = next_note_ptr;
                /* Check if we have reached the end of the note section. */
                if (curr_data_ptr >=
-                               curr_note_section_begin + stap_note_section_hdr->sh_size) {
+                               curr_note_section_begin +
+                                               stap_note_section_hdr.sh_size) {
                        *nb_probes = nb_match;
                        *offsets = probe_locs;
                        ret = 0;