cve/meltdown: use the snprintf function to prevent buffer overflow #1079
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Use the snprintf function instead of sprintf in the meltdown.c file to prevent buffer overflow.
Cause the length of the release in a struct utsname is unspecified.
struct utsname {
char sysname[]; /* Operating system name (e.g., "Linux") */
char nodename[]; /* Name within communications network
to which the node is attached, if any */
char release[]; /* Operating system release
(e.g., "2.6.28") */
char version[]; /* Operating system version */
char machine[]; /* Hardware type identifier */
#ifdef _GNU_SOURCE
char domainname[]; /* NIS or YP domain name */
#endif
};
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It appears that the struct member in question has its length specified by the libc implementation and can be accessed with |
| @@ -281,7 +281,7 @@ find_kernel_symbol(const char *name) | |||
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| if (uname(&utsname) < 0) | |||
| tst_brk(TBROK | TERRNO, "uname"); | |||
| sprintf(systemmap, "/boot/System.map-%s", utsname.release); | |||
| snprintf(systemmap, sizeof(systemmap), "/boot/System.map-%s", utsname.release); | |||
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systemmap is supposed to be null terminated. So you must reserve one byte for null and set it to zero.
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Actually as far as I can tell snprintf() always null terminates the output buffer, unless of course the buffer size passed is 0. So this patch looks good to me.
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@KunWuChan the patch is fine, but misses the signed-off-my line. See: https://www.kernel.org/doc/html/latest/process/submitting-patches.html?highlight=signed%20off#developer-s-certificate-of-origin-1-1
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thanks, I've update the comment.
Use the snprintf function instead of sprintf in the meltdown.c file to prevent buffer overflow.
Cause the length of the release in a struct utsname is unspecified.
struct utsname {
char sysname[]; /* Operating system name (e.g., "Linux") /
char nodename[]; / Name within communications network
to which the node is attached, if any /
char release[]; / Operating system release
(e.g., "2.6.28") /
char version[]; / Operating system version /
char machine[]; / Hardware type identifier /
#ifdef _GNU_SOURCE
char domainname[]; / NIS or YP domain name */
#endif
};
Signed-off-by: Kunwu Chan chentao@kylinos.cn