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fix(usercmd): Fix buffer overflow in uc_list() (neovim#23225)
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fix(usercmd): fix buffer overflow in uc_list()

Build with: -Wp,-D_FORTIFY_SOURCE=3 -O1 and gcc 13.

*** buffer overflow detected ***: terminated

(gdb) bt
  #0  __pthread_kill_implementation (threadid=<optimized out>, signo=signo@entry=6, no_tid=no_tid@entry=0) at pthread_kill.c:44
  #1  0x00007f3eb8b93c03 in __pthread_kill_internal (signo=6, threadid=<optimized out>) at pthread_kill.c:78
  #2  0x00007f3eb8b42aee in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26
  #3  0x00007f3eb8b2b87f in __GI_abort () at abort.c:79
  #4  0x00007f3eb8b2c60f in __libc_message (fmt=fmt@entry=0x7f3eb8ca72e6 "*** %s ***: terminated\n") at ../sysdeps/posix/libc_fatal.c:150
  #5  0x00007f3eb8c27b29 in __GI___fortify_fail (msg=msg@entry=0x7f3eb8ca728c "buffer overflow detected") at fortify_fail.c:24
  #6  0x00007f3eb8c26364 in __GI___chk_fail () at chk_fail.c:28
  neovim#7  0x00007f3eb8c25f45 in ___snprintf_chk (s=s@entry=0x55b8c7c096a5 <IObuff+5> "t' item", maxlen=maxlen@entry=1025, flag=flag@entry=2, slen=slen@entry=1020, format=format@entry=0x55b8c7b872a6 "%ldc") at snprintf_chk.c:29
  neovim#8  0x000055b8c7aea59f in snprintf (__fmt=0x55b8c7b872a6 "%ldc", __n=1025, __s=0x55b8c7c096a5 <IObuff+5> "t' item") at /usr/include/bits/stdio2.h:54
  neovim#9  uc_list (name=name@entry=0x55b8c8351788 "Explore", name_len=name_len@entry=7) at /usr/src/debug/neovim-0.9.0-1.fc38.x86_64/src/nvim/usercmd.c:534
  neovim#10 0x000055b8c7aeb8a0 in ex_command (eap=0x7fffdc350e60) at /usr/src/debug/neovim-0.9.0-1.fc38.x86_64/src/nvim/usercmd.c:1009
  neovim#11 0x000055b8c7972537 in execute_cmd0 (retv=retv@entry=0x7fffdc350e54, eap=eap@entry=0x7fffdc350e60, errormsg=errormsg@entry=0x7fffdc350e58, preview=preview@entry=false) at /usr/src/debug/neovim-0.9.0-1.fc38.x86_64/src/nvim/ex_docmd.c:1620
  neovim#12 0x000055b8c7975c55 in do_one_cmd (cmdlinep=cmdlinep@entry=0x7fffdc3510b8, flags=flags@entry=0, cstack=cstack@entry=0x7fffdc351140, fgetline=fgetline@entry=0x55b8c79882b8 <getexline>, cookie=cookie@entry=0x0) at /usr/src/debug/neovim-0.9.0-1.fc38.x86_64/src/nvim/ex_docmd.c:2279
  neovim#13 0x000055b8c79767fe in do_cmdline (cmdline=<optimized out>, fgetline=0x55b8c79882b8 <getexline>, cookie=0x0, flags=0) at /usr/src/debug/neovim-0.9.0-1.fc38.x86_64/src/nvim/ex_docmd.c:578
  neovim#14 0x000055b8c7a17463 in nv_colon (cap=0x7fffdc351780) at /usr/src/debug/neovim-0.9.0-1.fc38.x86_64/src/nvim/normal.c:3228
  neovim#15 0x000055b8c7a11b35 in normal_execute (state=0x7fffdc351700, key=<optimized out>) at /usr/src/debug/neovim-0.9.0-1.fc38.x86_64/src/nvim/normal.c:1196
  neovim#16 0x000055b8c7ab0994 in state_enter (s=0x7fffdc351700) at /usr/src/debug/neovim-0.9.0-1.fc38.x86_64/src/nvim/state.c:99
  neovim#17 0x000055b8c7a0ef68 in normal_enter (cmdwin=false, noexmode=false) at /usr/src/debug/neovim-0.9.0-1.fc38.x86_64/src/nvim/normal.c:497
  neovim#18 0x000055b8c78a0640 in main (argc=<optimized out>, argv=<optimized out>) at /usr/src/debug/neovim-0.9.0-1.fc38.x86_64/src/nvim/main.c:641
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@cryptomilk
cryptomilk authored Apr 21, 2023
1 parent ebfb639 commit 9e79f74
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Showing 2 changed files with 24 additions and 15 deletions.
34 changes: 19 additions & 15 deletions src/nvim/usercmd.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -469,7 +469,7 @@ static void uc_list(char *name, size_t name_len)
}

// Special cases
int len = 4;
size_t len = 4;
if (a & EX_BANG) {
msg_putchar('!');
len--;
Expand All @@ -491,7 +491,7 @@ static void uc_list(char *name, size_t name_len)
}

msg_outtrans_attr(cmd->uc_name, HL_ATTR(HLF_D));
len = (int)strlen(cmd->uc_name) + 4;
len = strlen(cmd->uc_name) + 4;

do {
msg_putchar(' ');
Expand All @@ -500,7 +500,7 @@ static void uc_list(char *name, size_t name_len)

// "over" is how much longer the name is than the column width for
// the name, we'll try to align what comes after.
const int over = len - 22;
const int64_t over = (int64_t)len - 22;
len = 0;

// Arguments
Expand All @@ -524,53 +524,57 @@ static void uc_list(char *name, size_t name_len)

do {
IObuff[len++] = ' ';
} while (len < 5 - over);
} while ((int64_t)len < 5 - over);

// Address / Range
if (a & (EX_RANGE | EX_COUNT)) {
if (a & EX_COUNT) {
// -count=N
snprintf(IObuff + len, IOSIZE, "%" PRId64 "c", cmd->uc_def);
len += (int)strlen(IObuff + len);
int rc = snprintf(IObuff + len, IOSIZE - len, "%" PRId64 "c", cmd->uc_def);
assert(rc > 0);
len += (size_t)rc;
} else if (a & EX_DFLALL) {
IObuff[len++] = '%';
} else if (cmd->uc_def >= 0) {
// -range=N
snprintf(IObuff + len, IOSIZE, "%" PRId64 "", cmd->uc_def);
len += (int)strlen(IObuff + len);
int rc = snprintf(IObuff + len, IOSIZE - len, "%" PRId64 "", cmd->uc_def);
assert(rc > 0);
len += (size_t)rc;
} else {
IObuff[len++] = '.';
}
}

do {
IObuff[len++] = ' ';
} while (len < 8 - over);
} while ((int64_t)len < 8 - over);

// Address Type
for (j = 0; addr_type_complete[j].expand != ADDR_NONE; j++) {
if (addr_type_complete[j].expand != ADDR_LINES
&& addr_type_complete[j].expand == cmd->uc_addr_type) {
STRCPY(IObuff + len, addr_type_complete[j].shortname);
len += (int)strlen(IObuff + len);
int rc = snprintf(IObuff + len, IOSIZE - len, "%s", addr_type_complete[j].shortname);
assert(rc > 0);
len += (size_t)rc;
break;
}
}

do {
IObuff[len++] = ' ';
} while (len < 13 - over);
} while ((int64_t)len < 13 - over);

// Completion
char *cmd_compl = get_command_complete(cmd->uc_compl);
if (cmd_compl != NULL) {
STRCPY(IObuff + len, get_command_complete(cmd->uc_compl));
len += (int)strlen(IObuff + len);
int rc = snprintf(IObuff + len, IOSIZE - len, "%s", get_command_complete(cmd->uc_compl));
assert(rc > 0);
len += (size_t)rc;
}

do {
IObuff[len++] = ' ';
} while (len < 25 - over);
} while ((int64_t)len < 25 - over);

IObuff[len] = '\0';
msg_outtrans(IObuff);
Expand Down
5 changes: 5 additions & 0 deletions test/functional/ex_cmds/excmd_spec.lua
View file
Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,11 @@ describe('Ex cmds', function()
assert_alive()
end)

it('listing long user command does not crash', function()
command('execute "command" repeat("T", 255) ":"')
command('command')
end)

it(':def is an unknown command #23149', function()
eq('Vim:E492: Not an editor command: def', pcall_err(command, 'def'))
eq(1, funcs.exists(':d'))
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