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ubifs: Fix out-of-bounds memory access caused by abnormal value of node_len

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In “ubifs_check_node”, when the value of "node_len" is abnormal,
the code will goto label of "out_len" for execution. Then, in the
following "ubifs_dump_node", if inode type is "UBIFS_DATA_NODE",
in "print_hex_dump", an out-of-bounds access may occur due to the
wrong "ch->len".

Therefore, when the value of "node_len" is abnormal, data length
should to be adjusted to a reasonable safe range. At this time,
structured data is not credible, so dump the corrupted data directly
for analysis.

Signed-off-by: Liu Song <liu.song11@zte.com.cn>
Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
Liu Song 2020-01-16 23:36:07 +08:00 committed by Richard Weinberger
parent 294a8dbe34
commit acc5af3efa
1 changed files with 14 additions and 2 deletions
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16
fs/ubifs/io.c
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@ -225,7 +225,7 @@ int ubifs_is_mapped(const struct ubifs_info *c, int lnum)
int ubifs_check_node(const struct ubifs_info *c, const void *buf, int lnum,
int offs, int quiet, int must_chk_crc)
{
int err = -EINVAL, type, node_len;
int err = -EINVAL, type, node_len, dump_node = 1;
uint32_t crc, node_crc, magic;
const struct ubifs_ch *ch = buf;
@ -278,10 +278,22 @@ int ubifs_check_node(const struct ubifs_info *c, const void *buf, int lnum,
out_len:
if (!quiet)
ubifs_err(c, "bad node length %d", node_len);
if (type == UBIFS_DATA_NODE && node_len > UBIFS_DATA_NODE_SZ)
dump_node = 0;
out:
if (!quiet) {
ubifs_err(c, "bad node at LEB %d:%d", lnum, offs);
ubifs_dump_node(c, buf);
if (dump_node) {
ubifs_dump_node(c, buf);
} else {
int safe_len = min3(node_len, c->leb_size - offs,
(int)UBIFS_MAX_DATA_NODE_SZ);
pr_err("\tprevent out-of-bounds memory access\n");
pr_err("\ttruncated data node length %d\n", safe_len);
pr_err("\tcorrupted data node:\n");
print_hex_dump(KERN_ERR, "\t", DUMP_PREFIX_OFFSET, 32, 1,
buf, safe_len, 0);
}
dump_stack();
}
return err;