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Work around bogus gcc-8.2 array-bounds warning/error 

gcc-8.2 is printing the following warning, which is an error
when used -Werror like our --enable-werror:

In file included from gprs_bssgp.c:34:
In function ‘tl16v_put’,
    inlined from ‘tvlv_put.part.3’ at ../../include/osmocom/gsm/tlv.h:156:9,
    inlined from ‘tvlv_put’ at ../../include/osmocom/gsm/tlv.h:147:24,
    inlined from ‘msgb_tvlv_push’ at ../../include/osmocom/gsm/tlv.h:386:2,
    inlined from ‘bssgp_tx_dl_ud’ at gprs_bssgp.c:1162:4:
../../include/osmocom/gsm/tlv.h:131:2: error: ‘memcpy’ forming offset [12, 130] is out of the bounds [0, 11] of object ‘mi’ with type ‘uint8_t[11]’ {aka ‘unsigned char[11]’} [-Werror=array-bounds]
  memcpy(buf, val, len);

Where "130" seems to be the maximum value of uint8_t, shifted right one +
2.  But even as we use strnlen() with "16" as maximum upper bound, gcc
still believes there's a way that the return value of gsm48_generate_mid_from_imsi()
could be 130.  In fact, even the newly-added OSMO_ASSERT() inside
gsm48_generate_mid() doesn't help and gcc still insists there is a problem :(

Change-Id: I0a06daa19b7b5b5badbb8b3d81a54c45b88a60ec
This commit is contained in:
Harald Welte 2019-01-20 13:45:31 +01:00
parent 1c3bae138c
commit 2033be8902
2 changed files with 21 additions and 1 deletions
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14
src/gb/gprs_bssgp.c
View File

@ -1157,10 +1157,17 @@ int bssgp_tx_dl_ud(struct msgb *msg, uint16_t pdu_lifetime,
/* IMSI */
if (dup->imsi && strlen(dup->imsi)) {
uint8_t mi[GSM48_MID_MAX_SIZE];
/* gsm48_generate_mid_from_imsi() is guaranteed to never return more than 11,
* but somehow gcc (8.2) is not smart enough to figure this out and claims that
* the memcpy in msgb_tvlv_put() below will cause and out-of-bounds access up to
* mi[131], which is wrong */
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Warray-bounds"
int imsi_len = gsm48_generate_mid_from_imsi(mi, dup->imsi);
if (imsi_len > 2)
msgb_tvlv_push(msg, BSSGP_IE_IMSI,
imsi_len-2, mi+2);
#pragma GCC diagnostic pop
}
/* DRX parameters */
@ -1220,7 +1227,14 @@ int bssgp_tx_paging(uint16_t nsei, uint16_t ns_bvci,
else
bgph->pdu_type = BSSGP_PDUT_PAGING_CS;
/* IMSI */
/* gsm48_generate_mid_from_imsi() is guaranteed to never return more than 11,
* but somehow gcc (8.2) is not smart enough to figure this out and claims that
* the memcpy in msgb_tvlv_put() below will cause and out-of-bounds access up to
* mi[131], which is wrong */
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Warray-bounds"
msgb_tvlv_put(msg, BSSGP_IE_IMSI, imsi_len-2, mi+2);
#pragma GCC diagnostic pop
/* DRX Parameters */
msgb_tvlv_put(msg, BSSGP_IE_DRX_PARAMS, 2,
(uint8_t *) &drx_params);

8
src/gb/gprs_bssgp_bss.c
View File

@ -183,10 +183,16 @@ int bssgp_tx_radio_status_imsi(struct bssgp_bvc_ctx *bctx, uint8_t cause,
if (!msg)
return -ENOMEM;
/* gsm48_generate_mid_from_imsi() is guaranteed to never return more than 11,
* but somehow gcc (8.2) is not smart enough to figure this out and claims that
* the memcpy in msgb_tvlv_put() below will cause and out-of-bounds access up to
* mi[131], which is wrong */
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Warray-bounds"
/* strip the MI type and length values (2 bytes) */
if (imsi_len > 2)
msgb_tvlv_put(msg, BSSGP_IE_IMSI, imsi_len-2, mi+2);
#pragma GCC diagnostic pop
LOGPC(DBSSGP, LOGL_NOTICE, "IMSI=%s ", imsi);
return common_tx_radio_status2(msg, cause);