> With fortify enabled gcc throws following error: > from mmc_cmds.c:20: > In function ‘read’, > inlined from ‘do_rpmb_write_key’ at mmc_cmds.c:2233:8: > /home/giuliobenetti/br_reproduce/a53922c5db3e605a5e81e53c034f45017e > bb7db7/output/host/mipsel-buildroot-linux- > gnu/sysroot/usr/include/bits/unistd.h:38:10: error: ‘__read_alias’ writing > 228 or more bytes into a region of size 32 overflows the destination [- > Werror=stringop-overflow=] > 38 | return __glibc_fortify (read, __nbytes, sizeof (char), > | ^~~~~~~~~~~~~~~ > mmc_cmds.c: In function ‘do_rpmb_write_key’: > mmc_cmds.c:2087:19: note: destination object ‘key_mac’ of size 32 > 2087 | u_int8_t key_mac[32]; > | ^~~~~~~ > /home/giuliobenetti/br_reproduce/a53922c5db3e605a5e81e53c034f45017e > bb7db7/output/host/mipsel-buildroot-linux- > gnu/sysroot/usr/include/bits/unistd.h:26:16: note: in a call to function > ‘__read_alias’ declared with attribute ‘access (write_only, 2, 3)’ > 26 | extern ssize_t __REDIRECT (__read_alias, (int __fd, void *__buf, > | ^~~~~~~~~~ > > read() could potentially return more than nbyte so let's check for ret < nbyte. No it can't because that would mean buffer overflow. See https://pubs.opengroup.org/onlinepubs/9699919799/functions/read.html : " this number shall never be greater than nbyte." So this seems like a bogus warning to me. Thanks, Avri > > Signed-off-by: Giulio Benetti <giulio.benetti@xxxxxxxxxxxxxxxxxxxxxx> > --- > mmc_cmds.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mmc_cmds.c b/mmc_cmds.c > index 10d063d..ae7b876 100644 > --- a/mmc_cmds.c > +++ b/mmc_cmds.c > @@ -2065,7 +2065,7 @@ int do_sanitize(int nargs, char **argv) > } \ > else if (r > 0) \ > ret += r; \ > - } while (r != 0 && (size_t)ret != nbyte); \ > + } while (r != 0 && (size_t)ret < nbyte); \ > \ > ret; \ > }) > -- > 2.34.1
