Fix: sessiond: unbounded elf section data size allocation

[lttng-tools.git] / src / common / lttng-elf.c

diff --git a/src/common/lttng-elf.c b/src/common/lttng-elf.c
index 5d4b93bbb80d13943571fede84f82057dea3a09d..91afcfdea3d19ae0435d655e4b49465064832d07 100644 (file)
--- a/src/common/lttng-elf.c
+++ b/src/common/lttng-elf.c
@@ -43,6 +43,7 @@
 #define NOTE_STAPSDT_SECTION_NAME ".note.stapsdt"
 #define NOTE_STAPSDT_NAME "stapsdt"
 #define NOTE_STAPSDT_TYPE 3
+#define MAX_SECTION_DATA_SIZE   512 * 1024 * 1024
 
 #if BYTE_ORDER == LITTLE_ENDIAN
 #define NATIVE_ELF_ENDIANNESS ELFDATA2LSB
@@ -191,6 +192,7 @@ struct lttng_elf_sym {
 
 struct lttng_elf {
        int fd;
+       size_t file_size;
        uint8_t bitness;
        uint8_t endianness;
        /* Offset in bytes to start of section names string table. */
@@ -531,16 +533,28 @@ struct lttng_elf *lttng_elf_create(int fd)
        struct lttng_elf_shdr section_names_shdr;
        struct lttng_elf *elf = NULL;
        int ret;
+       struct stat stat_buf;
 
        if (fd < 0) {
                goto error;
        }
 
+       ret = fstat(fd, &stat_buf);
+       if (ret) {
+               PERROR("Failed to determine size of elf file");
+               goto error;
+       }
+       if (!S_ISREG(stat_buf.st_mode)) {
+               ERR("Refusing to initialize lttng_elf from non-regular file");
+               goto error;
+       }
+
        elf = zmalloc(sizeof(struct lttng_elf));
        if (!elf) {
                PERROR("Error allocating struct lttng_elf");
                goto error;
        }
+       elf->file_size = (size_t) stat_buf.st_size;
 
        elf->fd = dup(fd);
        if (elf->fd < 0) {
@@ -632,6 +646,8 @@ char *lttng_elf_get_section_data(struct lttng_elf *elf,
        int ret;
        off_t section_offset;
        char *data;
+       const size_t max_alloc_size = min_t(size_t, MAX_SECTION_DATA_SIZE,
+                       elf->file_size);
 
        if (!elf || !shdr) {
                goto error;
@@ -643,6 +659,11 @@ char *lttng_elf_get_section_data(struct lttng_elf *elf,
                goto error;
        }
 
+       if (shdr->sh_size > max_alloc_size) {
+               ERR("ELF section size exceeds maximal allowed size of %zu bytes",
+                               max_alloc_size);
+               goto error;
+       }
        data = zmalloc(shdr->sh_size);
        if (!data) {
                PERROR("Error allocating buffer for ELF section data");