[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen staging-4.15] xz: validate the value before assigning it to an enum variable
commit cd751c09a5bab9f3529901fbe4d867ad7d52e89d Author: Lasse Collin <lasse.collin@xxxxxxxxxxx> AuthorDate: Thu Mar 10 09:51:29 2022 +0100 Commit: Jan Beulich <jbeulich@xxxxxxxx> CommitDate: Thu Mar 10 09:51:29 2022 +0100 xz: validate the value before assigning it to an enum variable This might matter, for example, if the underlying type of enum xz_check was a signed char. In such a case the validation wouldn't have caught an unsupported header. I don't know if this problem can occur in the kernel on any arch but it's still good to fix it because some people might copy the XZ code to their own projects from Linux instead of the upstream XZ Embedded repository. This change may increase the code size by a few bytes. An alternative would have been to use an unsigned int instead of enum xz_check but using an enumeration looks cleaner. Link: https://lore.kernel.org/r/20211010213145.17462-3-xiang@xxxxxxxxxx Signed-off-by: Lasse Collin <lasse.collin@xxxxxxxxxxx> Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx> Origin: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 4f8d7abaa413 Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx> Reviewed-by: Luca Fancellu <luca.fancellu@xxxxxxx> Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> master commit: 0a21660515c24f09c4ee060ce0bb42e4b2e6b6fa master date: 2022-03-07 09:08:54 +0100 --- xen/common/xz/dec_stream.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/xen/common/xz/dec_stream.c b/xen/common/xz/dec_stream.c index b8b566307c..e921d46abc 100644 --- a/xen/common/xz/dec_stream.c +++ b/xen/common/xz/dec_stream.c @@ -402,12 +402,12 @@ static enum xz_ret INIT dec_stream_header(struct xz_dec *s) * we will accept other check types too, but then the check won't * be verified and a warning (XZ_UNSUPPORTED_CHECK) will be given. */ + if (s->temp.buf[HEADER_MAGIC_SIZE + 1] > XZ_CHECK_MAX) + return XZ_OPTIONS_ERROR; + s->check_type = s->temp.buf[HEADER_MAGIC_SIZE + 1]; #ifdef XZ_DEC_ANY_CHECK - if (s->check_type > XZ_CHECK_MAX) - return XZ_OPTIONS_ERROR; - if (s->check_type > XZ_CHECK_CRC32) return XZ_UNSUPPORTED_CHECK; #else -- generated by git-patchbot for /home/xen/git/xen.git#staging-4.15
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