From acc5af3efa303d5f36cc8c0f61716161f6ca1384 Mon Sep 17 00:00:00 2001 From: Liu Song Date: Thu, 16 Jan 2020 23:36:07 +0800 Subject: ubifs: Fix out-of-bounds memory access caused by abnormal value of node_len MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Richard Weinberger --- fs/ubifs/io.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) (limited to 'fs/ubifs') diff --git a/fs/ubifs/io.c b/fs/ubifs/io.c index 8ceb51478800..7e4bfaf2871f 100644 --- a/fs/ubifs/io.c +++ b/fs/ubifs/io.c @@ -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; -- cgit v1.2.3