6.1-stable review patch. If anyone has any objections, please let me know.
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From: Paulo Alcantara pc@manguebit.com
commit eec04ea119691e65227a97ce53c0da6b9b74b0b7 upstream.
Fix potential OOB in receive_encrypted_standard() if server returned a large shdr->NextCommand that would end up writing off the end of @next_buffer.
Fixes: b24df3e30cbf ("cifs: update receive_encrypted_standard to handle compounded responses") Cc: stable@vger.kernel.org Reported-by: Robert Morris rtm@csail.mit.edu Signed-off-by: Paulo Alcantara (SUSE) pc@manguebit.com Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/smb/client/smb2ops.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-)
--- a/fs/smb/client/smb2ops.c +++ b/fs/smb/client/smb2ops.c @@ -5065,6 +5065,7 @@ receive_encrypted_standard(struct TCP_Se struct smb2_hdr *shdr; unsigned int pdu_length = server->pdu_size; unsigned int buf_size; + unsigned int next_cmd; struct mid_q_entry *mid_entry; int next_is_large; char *next_buffer = NULL; @@ -5093,14 +5094,15 @@ receive_encrypted_standard(struct TCP_Se next_is_large = server->large_buf; one_more: shdr = (struct smb2_hdr *)buf; - if (shdr->NextCommand) { + next_cmd = le32_to_cpu(shdr->NextCommand); + if (next_cmd) { + if (WARN_ON_ONCE(next_cmd > pdu_length)) + return -1; if (next_is_large) next_buffer = (char *)cifs_buf_get(); else next_buffer = (char *)cifs_small_buf_get(); - memcpy(next_buffer, - buf + le32_to_cpu(shdr->NextCommand), - pdu_length - le32_to_cpu(shdr->NextCommand)); + memcpy(next_buffer, buf + next_cmd, pdu_length - next_cmd); }
mid_entry = smb2_find_mid(server, buf); @@ -5124,8 +5126,8 @@ one_more: else ret = cifs_handle_standard(server, mid_entry);
- if (ret == 0 && shdr->NextCommand) { - pdu_length -= le32_to_cpu(shdr->NextCommand); + if (ret == 0 && next_cmd) { + pdu_length -= next_cmd; server->large_buf = next_is_large; if (next_is_large) server->bigbuf = buf = next_buffer;