| Message ID | 20240917150938.843879-1-alpernebiyasak@gmail.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Kalle Valo |
| Headers | show |
| Series | wifi: mwifiex: Fix memcpy() field-spanning write warning in mwifiex_config_scan() | expand |
On Tue, Sep 17, 2024 at 06:08:41PM +0300, Alper Nebi Yasak wrote: > Replace one-element array with a flexible-array member in `struct > mwifiex_ie_types_wildcard_ssid_params` to fix the following warning > on a MT8173 Chromebook (mt8173-elm-hana): > > [ 356.775250] ------------[ cut here ]------------ > [ 356.784543] memcpy: detected field-spanning write (size 6) of single field "wildcard_ssid_tlv->ssid" at drivers/net/wireless/marvell/mwifiex/scan.c:904 (size 1) > [ 356.813403] WARNING: CPU: 3 PID: 742 at drivers/net/wireless/marvell/mwifiex/scan.c:904 mwifiex_scan_networks+0x4fc/0xf28 [mwifiex] > > The "(size 6)" above is exactly the length of the SSID of the network > this device was connected to. The source of the warning looks like: > > ssid_len = user_scan_in->ssid_list[i].ssid_len; > [...] > memcpy(wildcard_ssid_tlv->ssid, > user_scan_in->ssid_list[i].ssid, ssid_len); > > Also adjust a #define that uses sizeof() on this struct to keep the > value same as before. ... > #define WILDCARD_SSID_TLV_MAX_SIZE \ > (MWIFIEX_MAX_SSID_LIST_LENGTH * \ > (sizeof(struct mwifiex_ie_types_wildcard_ssid_params) \ > - + IEEE80211_MAX_SSID_LEN)) > + + IEEE80211_MAX_SSID_LEN + 1)) > This hunk has to be carefully checked by wireless people. I'm not sure that we need + 1 here. Otherwise, LGTM.
On 9/17/24 7:30 PM, Andy Shevchenko wrote: > This hunk has to be carefully checked by wireless people. I'm not sure > that we need + 1 here. Well, +1 looks redundant here indeed. And if you touch this anyway, please also consider '__counted_by(max_ssid_length)' for 'ssid' (and test your kernel with CONFIG_KASAN enabled of course). Dmitry
On 9/17/2024 8:08 AM, Alper Nebi Yasak wrote: > Replace one-element array with a flexible-array member in `struct > mwifiex_ie_types_wildcard_ssid_params` to fix the following warning > on a MT8173 Chromebook (mt8173-elm-hana): > > [ 356.775250] ------------[ cut here ]------------ > [ 356.784543] memcpy: detected field-spanning write (size 6) of single field "wildcard_ssid_tlv->ssid" at drivers/net/wireless/marvell/mwifiex/scan.c:904 (size 1) > [ 356.813403] WARNING: CPU: 3 PID: 742 at drivers/net/wireless/marvell/mwifiex/scan.c:904 mwifiex_scan_networks+0x4fc/0xf28 [mwifiex] > > The "(size 6)" above is exactly the length of the SSID of the network > this device was connected to. The source of the warning looks like: > > ssid_len = user_scan_in->ssid_list[i].ssid_len; > [...] > memcpy(wildcard_ssid_tlv->ssid, > user_scan_in->ssid_list[i].ssid, ssid_len); > > Also adjust a #define that uses sizeof() on this struct to keep the > value same as before. > > Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com> > --- > I found these relevant patches that modify other such arrays, where the > second one removes a -1 from some sizeof() calculation: > > https://lore.kernel.org/lkml/Y9xkECG3uTZ6T1dN@work/T/#u > https://lore.kernel.org/lkml/ZsZa5xRcsLq9D+RX@elsanto/T/#u > > So I think we need the +1 to keep things same. But it appears to work > fine without it, so I'm not sure. Maybe it should've had a -1 before > that I would remove with this? I think the original code was incorrect and was allocating too much memory. I do not think WILDCARD_SSID_TLV_MAX_SIZE requires modification. > > drivers/net/wireless/marvell/mwifiex/fw.h | 2 +- > drivers/net/wireless/marvell/mwifiex/scan.c | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/wireless/marvell/mwifiex/fw.h b/drivers/net/wireless/marvell/mwifiex/fw.h > index d03129d5d24e..4a96281792cc 100644 > --- a/drivers/net/wireless/marvell/mwifiex/fw.h > +++ b/drivers/net/wireless/marvell/mwifiex/fw.h > @@ -875,7 +875,7 @@ struct mwifiex_ietypes_chanstats { > struct mwifiex_ie_types_wildcard_ssid_params { > struct mwifiex_ie_types_header header; > u8 max_ssid_length; > - u8 ssid[1]; > + u8 ssid[]; > } __packed; > > #define TSF_DATA_SIZE 8 > diff --git a/drivers/net/wireless/marvell/mwifiex/scan.c b/drivers/net/wireless/marvell/mwifiex/scan.c > index cab889af4c4a..50af78ee935b 100644 > --- a/drivers/net/wireless/marvell/mwifiex/scan.c > +++ b/drivers/net/wireless/marvell/mwifiex/scan.c > @@ -32,7 +32,7 @@ > #define WILDCARD_SSID_TLV_MAX_SIZE \ > (MWIFIEX_MAX_SSID_LIST_LENGTH * \ > (sizeof(struct mwifiex_ie_types_wildcard_ssid_params) \ > - + IEEE80211_MAX_SSID_LEN)) > + + IEEE80211_MAX_SSID_LEN + 1)) > > /* Maximum memory needed for a mwifiex_scan_cmd_config with all TLVs at max */ > #define MAX_SCAN_CFG_ALLOC (sizeof(struct mwifiex_scan_cmd_config) \ > > base-commit: 4f3e012d4cfd1d9bf837870c961f462ca9f23ebe
On 17/09/24 20:10, Jeff Johnson wrote: > On 9/17/2024 8:08 AM, Alper Nebi Yasak wrote: >> Replace one-element array with a flexible-array member in `struct >> mwifiex_ie_types_wildcard_ssid_params` to fix the following warning >> on a MT8173 Chromebook (mt8173-elm-hana): >> >> [ 356.775250] ------------[ cut here ]------------ >> [ 356.784543] memcpy: detected field-spanning write (size 6) of single field "wildcard_ssid_tlv->ssid" at drivers/net/wireless/marvell/mwifiex/scan.c:904 (size 1) >> [ 356.813403] WARNING: CPU: 3 PID: 742 at drivers/net/wireless/marvell/mwifiex/scan.c:904 mwifiex_scan_networks+0x4fc/0xf28 [mwifiex] >> >> The "(size 6)" above is exactly the length of the SSID of the network >> this device was connected to. The source of the warning looks like: >> >> ssid_len = user_scan_in->ssid_list[i].ssid_len; >> [...] >> memcpy(wildcard_ssid_tlv->ssid, >> user_scan_in->ssid_list[i].ssid, ssid_len); >> >> Also adjust a #define that uses sizeof() on this struct to keep the >> value same as before. >> >> Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com> >> --- >> I found these relevant patches that modify other such arrays, where the >> second one removes a -1 from some sizeof() calculation: >> >> https://lore.kernel.org/lkml/Y9xkECG3uTZ6T1dN@work/T/#u >> https://lore.kernel.org/lkml/ZsZa5xRcsLq9D+RX@elsanto/T/#u >> >> So I think we need the +1 to keep things same. But it appears to work >> fine without it, so I'm not sure. Maybe it should've had a -1 before >> that I would remove with this? > > I think the original code was incorrect and was allocating too much memory. > I do not think WILDCARD_SSID_TLV_MAX_SIZE requires modification. If this is case, I think the changelog text should include the following 'Fixes' tag (and the `__counted_by` annotation added in a separate patch): Fixes: 5e6e3a92b9a4 ("wireless: mwifiex: initial commit for Marvell mwifiex driver") Thanks -- Gustavo > >> >> drivers/net/wireless/marvell/mwifiex/fw.h | 2 +- >> drivers/net/wireless/marvell/mwifiex/scan.c | 2 +- >> 2 files changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/net/wireless/marvell/mwifiex/fw.h b/drivers/net/wireless/marvell/mwifiex/fw.h >> index d03129d5d24e..4a96281792cc 100644 >> --- a/drivers/net/wireless/marvell/mwifiex/fw.h >> +++ b/drivers/net/wireless/marvell/mwifiex/fw.h >> @@ -875,7 +875,7 @@ struct mwifiex_ietypes_chanstats { >> struct mwifiex_ie_types_wildcard_ssid_params { >> struct mwifiex_ie_types_header header; >> u8 max_ssid_length; >> - u8 ssid[1]; >> + u8 ssid[]; >> } __packed; >> >> #define TSF_DATA_SIZE 8 >> diff --git a/drivers/net/wireless/marvell/mwifiex/scan.c b/drivers/net/wireless/marvell/mwifiex/scan.c >> index cab889af4c4a..50af78ee935b 100644 >> --- a/drivers/net/wireless/marvell/mwifiex/scan.c >> +++ b/drivers/net/wireless/marvell/mwifiex/scan.c >> @@ -32,7 +32,7 @@ >> #define WILDCARD_SSID_TLV_MAX_SIZE \ >> (MWIFIEX_MAX_SSID_LIST_LENGTH * \ >> (sizeof(struct mwifiex_ie_types_wildcard_ssid_params) \ >> - + IEEE80211_MAX_SSID_LEN)) >> + + IEEE80211_MAX_SSID_LEN + 1)) >> >> /* Maximum memory needed for a mwifiex_scan_cmd_config with all TLVs at max */ >> #define MAX_SCAN_CFG_ALLOC (sizeof(struct mwifiex_scan_cmd_config) \ >> >> base-commit: 4f3e012d4cfd1d9bf837870c961f462ca9f23ebe >
On Tue, Sep 17, 2024 at 06:08:41PM +0300, Alper Nebi Yasak wrote: > Replace one-element array with a flexible-array member in `struct > mwifiex_ie_types_wildcard_ssid_params` to fix the following warning > on a MT8173 Chromebook (mt8173-elm-hana): > > [ 356.775250] ------------[ cut here ]------------ > [ 356.784543] memcpy: detected field-spanning write (size 6) of single field "wildcard_ssid_tlv->ssid" at drivers/net/wireless/marvell/mwifiex/scan.c:904 (size 1) > [ 356.813403] WARNING: CPU: 3 PID: 742 at drivers/net/wireless/marvell/mwifiex/scan.c:904 mwifiex_scan_networks+0x4fc/0xf28 [mwifiex] > > The "(size 6)" above is exactly the length of the SSID of the network > this device was connected to. The source of the warning looks like: > > ssid_len = user_scan_in->ssid_list[i].ssid_len; > [...] > memcpy(wildcard_ssid_tlv->ssid, > user_scan_in->ssid_list[i].ssid, ssid_len); > > Also adjust a #define that uses sizeof() on this struct to keep the > value same as before. > > Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com> > --- > I found these relevant patches that modify other such arrays, where the > second one removes a -1 from some sizeof() calculation: > > https://lore.kernel.org/lkml/Y9xkECG3uTZ6T1dN@work/T/#u > https://lore.kernel.org/lkml/ZsZa5xRcsLq9D+RX@elsanto/T/#u > > So I think we need the +1 to keep things same. But it appears to work > fine without it, so I'm not sure. Maybe it should've had a -1 before > that I would remove with this? Thanks for the investigation and patch! I believe I agree with the other comments, that then "+ 1" isn't necessary. It's just a wasteful extra byte of allocation. Can you send a v2? (Bonus: with the suggested Fixes tag. Double bonus if you test KASAN with __counted_by, for a second patch.) Thanks, Brian
diff --git a/drivers/net/wireless/marvell/mwifiex/fw.h b/drivers/net/wireless/marvell/mwifiex/fw.h index d03129d5d24e..4a96281792cc 100644 --- a/drivers/net/wireless/marvell/mwifiex/fw.h +++ b/drivers/net/wireless/marvell/mwifiex/fw.h @@ -875,7 +875,7 @@ struct mwifiex_ietypes_chanstats { struct mwifiex_ie_types_wildcard_ssid_params { struct mwifiex_ie_types_header header; u8 max_ssid_length; - u8 ssid[1]; + u8 ssid[]; } __packed; #define TSF_DATA_SIZE 8 diff --git a/drivers/net/wireless/marvell/mwifiex/scan.c b/drivers/net/wireless/marvell/mwifiex/scan.c index cab889af4c4a..50af78ee935b 100644 --- a/drivers/net/wireless/marvell/mwifiex/scan.c +++ b/drivers/net/wireless/marvell/mwifiex/scan.c @@ -32,7 +32,7 @@ #define WILDCARD_SSID_TLV_MAX_SIZE \ (MWIFIEX_MAX_SSID_LIST_LENGTH * \ (sizeof(struct mwifiex_ie_types_wildcard_ssid_params) \ - + IEEE80211_MAX_SSID_LEN)) + + IEEE80211_MAX_SSID_LEN + 1)) /* Maximum memory needed for a mwifiex_scan_cmd_config with all TLVs at max */ #define MAX_SCAN_CFG_ALLOC (sizeof(struct mwifiex_scan_cmd_config) \
Replace one-element array with a flexible-array member in `struct mwifiex_ie_types_wildcard_ssid_params` to fix the following warning on a MT8173 Chromebook (mt8173-elm-hana): [ 356.775250] ------------[ cut here ]------------ [ 356.784543] memcpy: detected field-spanning write (size 6) of single field "wildcard_ssid_tlv->ssid" at drivers/net/wireless/marvell/mwifiex/scan.c:904 (size 1) [ 356.813403] WARNING: CPU: 3 PID: 742 at drivers/net/wireless/marvell/mwifiex/scan.c:904 mwifiex_scan_networks+0x4fc/0xf28 [mwifiex] The "(size 6)" above is exactly the length of the SSID of the network this device was connected to. The source of the warning looks like: ssid_len = user_scan_in->ssid_list[i].ssid_len; [...] memcpy(wildcard_ssid_tlv->ssid, user_scan_in->ssid_list[i].ssid, ssid_len); Also adjust a #define that uses sizeof() on this struct to keep the value same as before. Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com> --- I found these relevant patches that modify other such arrays, where the second one removes a -1 from some sizeof() calculation: https://lore.kernel.org/lkml/Y9xkECG3uTZ6T1dN@work/T/#u https://lore.kernel.org/lkml/ZsZa5xRcsLq9D+RX@elsanto/T/#u So I think we need the +1 to keep things same. But it appears to work fine without it, so I'm not sure. Maybe it should've had a -1 before that I would remove with this? drivers/net/wireless/marvell/mwifiex/fw.h | 2 +- drivers/net/wireless/marvell/mwifiex/scan.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) base-commit: 4f3e012d4cfd1d9bf837870c961f462ca9f23ebe