From: Eugene Korenevsky Date: Mon, 13 Oct 2025 18:39:30 +0000 (+0300) Subject: cifs: parse_dfs_referrals: prevent oob on malformed input X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=6447b0e355562a1ff748c4a2ffb89aae7e84d2c9;p=users%2Fhch%2Fmisc.git cifs: parse_dfs_referrals: prevent oob on malformed input Malicious SMB server can send invalid reply to FSCTL_DFS_GET_REFERRALS - reply smaller than sizeof(struct get_dfs_referral_rsp) - reply with number of referrals smaller than NumberOfReferrals in the header Processing of such replies will cause oob. Return -EINVAL error on such replies to prevent oob-s. Signed-off-by: Eugene Korenevsky Cc: stable@vger.kernel.org Suggested-by: Nathan Chancellor Acked-by: Paulo Alcantara (Red Hat) Signed-off-by: Steve French --- diff --git a/fs/smb/client/misc.c b/fs/smb/client/misc.c index dda6dece802a..e10123d8cd7d 100644 --- a/fs/smb/client/misc.c +++ b/fs/smb/client/misc.c @@ -916,6 +916,14 @@ parse_dfs_referrals(struct get_dfs_referral_rsp *rsp, u32 rsp_size, char *data_end; struct dfs_referral_level_3 *ref; + if (rsp_size < sizeof(*rsp)) { + cifs_dbg(VFS | ONCE, + "%s: header is malformed (size is %u, must be %zu)\n", + __func__, rsp_size, sizeof(*rsp)); + rc = -EINVAL; + goto parse_DFS_referrals_exit; + } + *num_of_nodes = le16_to_cpu(rsp->NumberOfReferrals); if (*num_of_nodes < 1) { @@ -925,6 +933,15 @@ parse_dfs_referrals(struct get_dfs_referral_rsp *rsp, u32 rsp_size, goto parse_DFS_referrals_exit; } + if (sizeof(*rsp) + *num_of_nodes * sizeof(REFERRAL3) > rsp_size) { + cifs_dbg(VFS | ONCE, + "%s: malformed buffer (size is %u, must be at least %zu)\n", + __func__, rsp_size, + sizeof(*rsp) + *num_of_nodes * sizeof(REFERRAL3)); + rc = -EINVAL; + goto parse_DFS_referrals_exit; + } + ref = (struct dfs_referral_level_3 *) &(rsp->referrals); if (ref->VersionNumber != cpu_to_le16(3)) { cifs_dbg(VFS, "Referrals of V%d version are not supported, should be V3\n",