mirror of
https://github.com/freebsd/freebsd-src
synced 2024-09-06 17:18:32 +00:00
![]() `iconv_sysctl_add` from `sys/libkern/iconv.c` incorrectly limits the size of user strings, such that several out of bounds reads could have been possible. static int iconv_sysctl_add(SYSCTL_HANDLER_ARGS) { struct iconv_converter_class *dcp; struct iconv_cspair *csp; struct iconv_add_in din; struct iconv_add_out dout; int error; error = SYSCTL_IN(req, &din, sizeof(din)); if (error) return error; if (din.ia_version != ICONV_ADD_VER) return EINVAL; if (din.ia_datalen > ICONV_CSMAXDATALEN) return EINVAL; if (strlen(din.ia_from) >= ICONV_CSNMAXLEN) return EINVAL; if (strlen(din.ia_to) >= ICONV_CSNMAXLEN) return EINVAL; if (strlen(din.ia_converter) >= ICONV_CNVNMAXLEN) return EINVAL; ... Since the `din` struct is directly copied from userland, there is no guarantee that the strings supplied will be NULL terminated. The `strlen` calls could continue reading past the designated buffer sizes. Declaration of `struct iconv_add_in` is found in `sys/sys/iconv.h`: struct iconv_add_in { int ia_version; char ia_converter[ICONV_CNVNMAXLEN]; char ia_to[ICONV_CSNMAXLEN]; char ia_from[ICONV_CSNMAXLEN]; int ia_datalen; const void *ia_data; }; Our strings are followed by the `ia_datalen` member, which is checked before the `strlen` calls: if (din.ia_datalen > ICONV_CSMAXDATALEN) Since `ICONV_CSMAXDATALEN` has value `0x41000` (and is `unsigned`), this ensures that `din.ia_datalen` contains at least 1 byte of 0, so it is not possible to trigger a read out of bounds of the `struct` however, this code is fragile and could introduce subtle bugs in the future if the `struct` is ever modified. PR: 207302 Submitted by: CTurt <cturt@hardenedbsd.org> Reported by: CTurt <cturt@hardenedbsd.org> Reviewed by: jhb, vangyzen MFC after: 1 week Sponsored by: Dell EMC Differential Revision: https://reviews.freebsd.org/D14521 |
||
---|---|---|
.. | ||
amd64 | ||
arm | ||
arm64 | ||
bsm | ||
cam | ||
cddl | ||
compat | ||
conf | ||
contrib | ||
crypto | ||
ddb | ||
dev | ||
dts | ||
fs | ||
gdb | ||
geom | ||
gnu | ||
i386 | ||
isa | ||
kern | ||
kgssapi | ||
libkern | ||
mips | ||
modules | ||
net | ||
net80211 | ||
netgraph | ||
netinet | ||
netinet6 | ||
netipsec | ||
netpfil | ||
netsmb | ||
nfs | ||
nfsclient | ||
nfsserver | ||
nlm | ||
ofed | ||
opencrypto | ||
powerpc | ||
riscv | ||
rpc | ||
security | ||
sparc64 | ||
sys | ||
teken | ||
tests | ||
tools | ||
ufs | ||
vm | ||
x86 | ||
xdr | ||
xen | ||
Makefile |