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FROMGIT: libfdt: fdt_path_offset_namelen: Reject empty path

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Reject empty paths and negative lengths, according to the DT spec v0.4:

    The convention for specifying a device path is:
        /node-name-1/node-name-2/node-name-N

    The path to the root node is /.

This prevents the access to path[0] from ever being out-of-bounds.

Signed-off-by: Pierre-Clément Tosi <ptosi@google.com>
Message-ID: <20231010092822.qo2nxc3g47t26dqs@google.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

Test: N/A
Change-Id: I8efee39a06fa62f1f057a975e8133a295be0a656
This commit is contained in:
Pierre-Clément Tosi 2023-10-10 10:28:22 +01:00
parent 10b6dbab70
commit b202d115bd
2 changed files with 10 additions and 1 deletions
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3
libfdt/fdt_ro.c
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@ -263,6 +263,9 @@ int fdt_path_offset_namelen(const void *fdt, const char *path, int namelen)
FDT_RO_PROBE(fdt);
if (!can_assume(VALID_INPUT) && namelen <= 0)
return -FDT_ERR_BADPATH;
/* see if we have an alias */
if (*path != '/') {
const char *q = memchr(path, '/', end - p);

8
tests/path_offset.c
View file

@ -48,10 +48,13 @@ static void check_path_offset(void *fdt, char *path, int offset)
verbose_printf("Checking offset of \"%s\" is %d...\n", path, offset);
rc = fdt_path_offset(fdt, path);
if (rc == offset)
return;
if (rc < 0)
FAIL("fdt_path_offset(\"%s\") failed: %s",
path, fdt_strerror(rc));
if (rc != offset)
else
FAIL("fdt_path_offset(\"%s\") returned incorrect offset"
" %d instead of %d", path, rc, offset);
}
@ -102,6 +105,7 @@ int main(int argc, char *argv[])
check_path_offset(fdt, "/subnode@2/subsubnode", subsubnode2_offset2);
/* Test paths with extraneous separators */
check_path_offset(fdt, "", -FDT_ERR_BADPATH);
check_path_offset(fdt, "//", 0);
check_path_offset(fdt, "///", 0);
check_path_offset(fdt, "//subnode@1", subnode1_offset);
@ -110,6 +114,8 @@ int main(int argc, char *argv[])
check_path_offset(fdt, "/subnode@2////subsubnode", subsubnode2_offset2);
/* Test fdt_path_offset_namelen() */
check_path_offset_namelen(fdt, "/subnode@1", -1, -FDT_ERR_BADPATH);
check_path_offset_namelen(fdt, "/subnode@1", 0, -FDT_ERR_BADPATH);
check_path_offset_namelen(fdt, "/subnode@1", 1, 0);
check_path_offset_namelen(fdt, "/subnode@1/subsubnode", 10, subnode1_offset);
check_path_offset_namelen(fdt, "/subnode@1/subsubnode", 11, subnode1_offset);