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| author | Cy Schubert <cy@FreeBSD.org> | 2023-02-02 00:49:08 +0000 |
|---|---|---|
| committer | Cy Schubert <cy@FreeBSD.org> | 2023-02-09 21:20:51 +0000 |
| commit | 351f2f68852ac3e1d0ef745dc024dd745b07a34f (patch) | |
| tree | 59e52535acdb9401cd58b6a8323f621c7d305d2a | |
| parent | 272b2e191eadbd267e173e0ed4d9e19e48c97674 (diff) | |
| download | src-351f2f68852ac3e1d0ef745dc024dd745b07a34f.tar.gz src-351f2f68852ac3e1d0ef745dc024dd745b07a34f.zip | |
ipfilter: Fix use after free on packet with broken lengths
Under the scenario with a packet with length of 67 bytes, a header length
using the default of 20 bytes and a TCP data offset (th_off) of 48 will
cause m_pullup() to fail to make sure bytes are arragned contiguously.
m_pullup() will free the mbuf chain and return a null. ipfilter stores
the resultant mbuf address (or the resulting NULL) in its fr_info_t
structure. Unfortuntely the eroneous packet is not flagged for drop.
This results in a kernel page fault at line 410 of sys/netinet/ip_fastfwd.c
as it tries to use a now previously freed, by m_pullup(), mbuf.
PR: 266442
Reported by: Robert Morris <rtm@lcs.mit.edu>
(cherry picked from commit 79f7745c098a766d34a4e072cdd1a06e6d0829d5)
| -rw-r--r-- | sys/netpfil/ipfilter/netinet/fil.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/sys/netpfil/ipfilter/netinet/fil.c b/sys/netpfil/ipfilter/netinet/fil.c index 4fa90f64fb33..3cf9111340a3 100644 --- a/sys/netpfil/ipfilter/netinet/fil.c +++ b/sys/netpfil/ipfilter/netinet/fil.c @@ -1113,8 +1113,10 @@ ipf_pr_pullup(fr_info_t *fin, int plen) if (M_LEN(fin->fin_m) < plen + fin->fin_ipoff) { #if defined(_KERNEL) if (ipf_pullup(fin->fin_m, fin, plen) == NULL) { - DT(ipf_pullup_fail); + DT1(ipf_pullup_fail, fr_info_t *, fin); LBUMP(ipf_stats[fin->fin_out].fr_pull[1]); + fin->fin_reason = FRB_PULLUP; + fin->fin_flx |= FI_BAD; return (-1); } LBUMP(ipf_stats[fin->fin_out].fr_pull[0]); @@ -1127,6 +1129,7 @@ ipf_pr_pullup(fr_info_t *fin, int plen) *fin->fin_mp = NULL; fin->fin_m = NULL; fin->fin_ip = NULL; + fin->fin_flx |= FI_BAD; return (-1); #endif } @@ -3180,6 +3183,14 @@ finished: SPL_X(s); + if (fin->fin_m == NULL && fin->fin_flx & FI_BAD && + fin->fin_reason == FRB_PULLUP) { + /* m_pullup() has freed the mbuf */ + LBUMP(ipf_stats[out].fr_blocked[fin->fin_reason]); + return (-1); + } + + #ifdef _KERNEL if (FR_ISPASS(pass)) return (0); |