@@ -21,14 +21,21 @@
#include "qemu/osdep.h"
#include "qemu/cutils.h"
+#include "qemu/error-report.h"
#include "hw/nvram/chrp_nvram.h"
#include "sysemu/sysemu.h"
-static int chrp_nvram_set_var(uint8_t *nvram, int addr, const char *str)
+static int chrp_nvram_set_var(uint8_t *nvram, int addr, const char *str,
+ int max_len)
{
int len;
len = strlen(str) + 1;
+
+ if (max_len < len) {
+ return -1;
+ }
+
memcpy(&nvram[addr], str, len);
return addr + len;
@@ -38,19 +45,26 @@ static int chrp_nvram_set_var(uint8_t *nvram, int addr, const char *str)
* Create a "system partition", used for the Open Firmware
* environment variables.
*/
-int chrp_nvram_create_system_partition(uint8_t *data, int min_len)
+int chrp_nvram_create_system_partition(uint8_t *data, int min_len, int max_len)
{
ChrpNvramPartHdr *part_header;
unsigned int i;
int end;
+ if (max_len < sizeof(*part_header)) {
+ goto fail;
+ }
+
part_header = (ChrpNvramPartHdr *)data;
part_header->signature = CHRP_NVPART_SYSTEM;
pstrcpy(part_header->name, sizeof(part_header->name), "system");
end = sizeof(ChrpNvramPartHdr);
for (i = 0; i < nb_prom_envs; i++) {
- end = chrp_nvram_set_var(data, end, prom_envs[i]);
+ end = chrp_nvram_set_var(data, end, prom_envs[i], max_len - end);
+ if (end == -1) {
+ goto fail;
+ }
}
/* End marker */
@@ -65,6 +79,10 @@ int chrp_nvram_create_system_partition(uint8_t *data, int min_len)
chrp_nvram_finish_partition(part_header, end);
return end;
+
+fail:
+ error_report("NVRAM is too small. Try to pass less data to -prom-env");
+ exit(EXIT_FAILURE);
}
/**
@@ -141,7 +141,7 @@ static void pmac_format_nvram_partition_of(MacIONVRAMState *nvr, int off,
/* OpenBIOS nvram variables partition */
sysp_end = chrp_nvram_create_system_partition(&nvr->data[off],
- DEF_SYSTEM_SIZE) + off;
+ DEF_SYSTEM_SIZE, len) + off;
/* Free space partition */
chrp_nvram_create_free_partition(&nvr->data[sysp_end], len - sysp_end);
@@ -188,7 +188,8 @@ static void spapr_nvram_realize(SpaprVioDevice *dev, Error **errp)
}
} else if (nb_prom_envs > 0) {
/* Create a system partition to pass the -prom-env variables */
- chrp_nvram_create_system_partition(nvram->buf, MIN_NVRAM_SIZE / 4);
+ chrp_nvram_create_system_partition(nvram->buf, MIN_NVRAM_SIZE / 4,
+ nvram->size);
chrp_nvram_create_free_partition(&nvram->buf[MIN_NVRAM_SIZE / 4],
nvram->size - MIN_NVRAM_SIZE / 4);
}
@@ -143,7 +143,7 @@ static void nvram_init(Nvram *nvram, uint8_t *macaddr,
memset(image, '\0', sizeof(image));
/* OpenBIOS nvram variables partition */
- sysp_end = chrp_nvram_create_system_partition(image, 0);
+ sysp_end = chrp_nvram_create_system_partition(image, 0, sizeof(image));
/* Free space partition */
chrp_nvram_create_free_partition(&image[sysp_end], 0x1fd0 - sysp_end);
@@ -136,7 +136,7 @@ static int sun4u_NVRAM_set_params(Nvram *nvram, uint16_t NVRAM_size,
memset(image, '\0', sizeof(image));
/* OpenBIOS nvram variables partition */
- sysp_end = chrp_nvram_create_system_partition(image, 0);
+ sysp_end = chrp_nvram_create_system_partition(image, 0, sizeof(image));
/* Free space partition */
chrp_nvram_create_free_partition(&image[sysp_end], 0x1fd0 - sysp_end);
@@ -50,7 +50,8 @@ chrp_nvram_finish_partition(ChrpNvramPartHdr *header, uint32_t size)
header->checksum = sum & 0xff;
}
-int chrp_nvram_create_system_partition(uint8_t *data, int min_len);
+/* chrp_nvram_create_system_partition() failure is fatal */
+int chrp_nvram_create_system_partition(uint8_t *data, int min_len, int max_len);
int chrp_nvram_create_free_partition(uint8_t *data, int len);
#endif
Since commit 61f20b9dc5b7 ("spapr_nvram: Pre-initialize the NVRAM to support the -prom-env parameter"), pseries machines can pre-initialize the "system" partition in the NVRAM with the data passed to all -prom-env parameters on the QEMU command line. In this case it is assumed that all the data fits in 64 KiB, but the user can easily pass more and crash QEMU: $ qemu-system-ppc64 -M pseries $(for ((x=0;x<128;x++)); do \ echo -n " -prom-env " ; printf "%0.sx" {1..1024}; \ done) # this requires ~128 Kib malloc(): corrupted top size Aborted (core dumped) This happens because we don't check if all the prom-env data fits in the NVRAM and chrp_nvram_set_var() happily memcpy() it passed the buffer. This crash affects basically all ppc/ppc64 machine types that use -prom-env: - pseries (all versions) - g3beige - mac99 and also sparc/sparc64 machine types: - LX - SPARCClassic - SPARCbook - SS-10 - SS-20 - SS-4 - SS-5 - SS-600MP - Voyager - sun4u - sun4v Add a max_len argument to chrp_nvram_create_system_partition() so that it can check the available size before writing to memory. Since NVRAM is populated at machine init, it seems reasonable to consider this error as fatal. So, instead of reporting an error when we detect that the NVRAM is too small and adapt all machine types to handle it, we simply exit QEMU in all cases. This is still better than crashing. If someone wants another behavior, I guess this can be reworked later. Tested with: $ yes q | \ (for arch in ppc ppc64 sparc sparc64; do \ echo == $arch ==; \ qemu=${arch}-softmmu/qemu-system-$arch; \ for mach in $($qemu -M help | awk '! /^Supported/ { print $1 }'); do \ echo $mach; \ $qemu -M $mach -monitor stdio -nodefaults -nographic \ $(for ((x=0;x<128;x++)); do \ echo -n " -prom-env " ; printf "%0.sx" {1..1024}; \ done) >/dev/null; \ done; echo; \ done) Without the patch, affected machine types cause QEMU to report some memory corruption and crash: malloc(): corrupted top size free(): invalid size *** stack smashing detected ***: terminated With the patch, QEMU prints the following message and exits: NVRAM is too small. Try to pass less data to -prom-env It seems that the conditions for the crash have always existed, but it affects pseries, the machine type I care for, since commit 61f20b9dc5b7 only. Fixes: 61f20b9dc5b7 ("spapr_nvram: Pre-initialize the NVRAM to support the -prom-env parameter") RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=1867739 Reported-by: John Snow <jsnow@redhat.com> Signed-off-by: Greg Kurz <groug@kaod.org> --- This replaces the following series: [PATCH v2 0/2] spapr/nvram: Fix QEMU crash http://patchwork.ozlabs.org/project/qemu-devel/list/?series=195269 --- hw/nvram/chrp_nvram.c | 24 +++++++++++++++++++++--- hw/nvram/mac_nvram.c | 2 +- hw/nvram/spapr_nvram.c | 3 ++- hw/sparc/sun4m.c | 2 +- hw/sparc64/sun4u.c | 2 +- include/hw/nvram/chrp_nvram.h | 3 ++- 6 files changed, 28 insertions(+), 8 deletions(-)