@@ -74,6 +74,12 @@
#define MAX_SHARED_LIBS (1)
#endif
+#ifdef FLAT_TEXT_DATA_NO_GAP
+#define DATA_GAP_WORDS (0)
+#else
+#define DATA_GAP_WORDS (MAX_SHARED_LIBS)
+#endif
+
struct lib_info {
struct {
unsigned long start_code; /* Start of text segment */
@@ -437,7 +443,6 @@ static int load_flat_file(struct linux_binprm *bprm,
__be32 __user *reloc;
u32 __user *rp;
int i, rev, relocs;
- loff_t fpos;
unsigned long start_code, end_code;
ssize_t result;
int ret;
@@ -560,6 +565,9 @@ static int load_flat_file(struct linux_binprm *bprm,
* it all together.
*/
if (!IS_ENABLED(CONFIG_MMU) && !(flags & (FLAT_FLAG_RAM|FLAT_FLAG_GZIP))) {
+#ifndef FLAT_TEXT_DATA_NO_GAP
+ loff_t fpos;
+
/*
* this should give us a ROM ptr, but if it doesn't we don't
* really care
@@ -576,7 +584,7 @@ static int load_flat_file(struct linux_binprm *bprm,
goto err;
}
- len = data_len + extra + MAX_SHARED_LIBS * sizeof(unsigned long);
+ len = data_len + extra + DATA_GAP_WORDS * sizeof(unsigned long);
len = PAGE_ALIGN(len);
realdatastart = vm_mmap(NULL, 0, len,
PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE, 0);
@@ -591,7 +599,7 @@ static int load_flat_file(struct linux_binprm *bprm,
goto err;
}
datapos = ALIGN(realdatastart +
- MAX_SHARED_LIBS * sizeof(unsigned long),
+ DATA_GAP_WORDS * sizeof(unsigned long),
FLAT_DATA_ALIGN);
pr_debug("Allocated data+bss+stack (%u bytes): %lx\n",
@@ -620,9 +628,14 @@ static int load_flat_file(struct linux_binprm *bprm,
(datapos + (ntohl(hdr->reloc_start) - text_len));
memp = realdatastart;
memp_size = len;
+#else
+ pr_err("Separate text/data loading not supported\n");
+ ret = -ENOEXEC;
+ goto err;
+#endif /* FLAT_TEXT_DATA_NO_GAP */
} else {
- len = text_len + data_len + extra + MAX_SHARED_LIBS * sizeof(u32);
+ len = text_len + data_len + extra + DATA_GAP_WORDS * sizeof(u32);
len = PAGE_ALIGN(len);
textpos = vm_mmap(NULL, 0, len,
PROT_READ | PROT_EXEC | PROT_WRITE, MAP_PRIVATE, 0);
@@ -638,7 +651,7 @@ static int load_flat_file(struct linux_binprm *bprm,
realdatastart = textpos + ntohl(hdr->data_start);
datapos = ALIGN(realdatastart +
- MAX_SHARED_LIBS * sizeof(u32),
+ DATA_GAP_WORDS * sizeof(u32),
FLAT_DATA_ALIGN);
reloc = (__be32 __user *)
@@ -714,7 +727,7 @@ static int load_flat_file(struct linux_binprm *bprm,
ret = result;
pr_err("Unable to read code+data+bss, errno %d\n", ret);
vm_munmap(textpos, text_len + data_len + extra +
- MAX_SHARED_LIBS * sizeof(u32));
+ DATA_GAP_WORDS * sizeof(u32));
goto err;
}
}
Commit 2217b9826246 ("binfmt_flat: revert "binfmt_flat: don't offset the data start"") restored offsetting the start of the data section by a number of words defined by MAX_SHARED_LIBS. As a result, since MAX_SHARED_LIBS is never 0, a gap between the text and data sections always exist. For architecture which cannot support a such gap between the text and data sections (e.g. riscv nommu), flat binary programs cannot be executed. To allow an architecture to request contiguous text and data sections, introduce the macro FLAT_TEXT_DATA_NO_GAP which can be defined by the architecture in its asm/flat.h file. With this change, the macro DATA_GAP_WORDS is conditionally defined in binfmt_flat.c to MAX_SHARED_LIBS for architectures tolerating the gap (FLAT_TEXT_DATA_NO_GAP undefined case) and to 0 when FLAT_TEXT_DATA_NO_GAP is defined. DATA_GAP_WORDS is used in load_flat_file() to calculate the data section length and start position. The definition of FLAT_TEXT_DATA_NO_GAP by an architecture also prevents the use of the separate text/data load case (when FLAT_FLAG_RAM and FLAT_FLAG_GZIP are not set with NOMMU kernels). Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> --- fs/binfmt_flat.c | 25 +++++++++++++++++++------ 1 file changed, 19 insertions(+), 6 deletions(-)