Re: [PATCH net v4 1/2] net: stmmac: replace memcpy with ethtool_puts in ethtool
flat view
From: Andrew Lunn <andrew@lunn.ch>
Date: 2025-09-16 17:12:30
Also in:
lkml
On Tue, Sep 16, 2025 at 05:45:30PM +0100, Simon Horman wrote:
On Tue, Sep 16, 2025 at 02:09:31PM +0200, Konrad Leszczynski wrote:quoted
Fix kernel exception by replacing memcpy with ethtool_puts when used with safety feature strings in ethtool logic. [ +0.000023] BUG: KASAN: global-out-of-bounds in stmmac_get_strings+0x17d/0x520 [stmmac] [ +0.000115] Read of size 32 at addr ffffffffc0cfab20 by task ethtool/2571 [ +0.000005] Call Trace: [ +0.000004] <TASK> [ +0.000003] dump_stack_lvl+0x6c/0x90 [ +0.000016] print_report+0xce/0x610 [ +0.000011] ? stmmac_get_strings+0x17d/0x520 [stmmac] [ +0.000108] ? kasan_addr_to_slab+0xd/0xa0 [ +0.000008] ? stmmac_get_strings+0x17d/0x520 [stmmac] [ +0.000101] kasan_report+0xd4/0x110 [ +0.000010] ? stmmac_get_strings+0x17d/0x520 [stmmac] [ +0.000102] kasan_check_range+0x3a/0x1c0 [ +0.000010] __asan_memcpy+0x24/0x70 [ +0.000008] stmmac_get_strings+0x17d/0x520 [stmmac] Reviewed-by: Sebastian Basierski <redacted> Reviewed-by: Cezary Rojewski <cezary.rojewski@intel.com> Signed-off-by: Konrad Leszczynski <redacted>As per my comment on v3 (sorry, I missed that you had already posted v4): I think it would be good to explain why using memcpy() is a problem here. I looked and it seems to me that one reason is that the strings may be too long.
I actually think the strings are too short. But i could be wrong.
In general, stmmac uses:
struct stmmac_stats {
char stat_string[ETH_GSTRING_LEN] __nonstring;
int sizeof_stat;
int stat_offset;
};
so the string is guaranteed to be long enough. However, these 'safety'
features make use of
struct dwmac5_error_desc {
bool valid;
const char *desc;
const char *detailed_desc;
};
where desc can be any length, ironically making
dwmac5_safety_feat_dump() unsafe. This is why i asked that this be
changed to be the same stmmac_stats, so [ETH_GSTRING_LEN]
__nonstring. But that seems to of fallen on deaf ears.
Andrew